Unless our course is altered, it is we who will unwind the miraculous spiral of the sea.
The shell was unlike any I’d ever seen, set apart from the countless marine housings on the shore not only by its extraordinary beauty but also its extravagant size. As big as a side plate heaped high at a buffet when I held it in my hand, its thick coil of creamy white calcium carbonate was swirled through with butterscotch whorls like a tub of ice cream. Against skin it felt as smooth as polished glass, and a pool of mother of pearl gleamed its gasoline sheen of oily iridescence on the inner lip of the opening. I stood there on the beach and admired the contours and curvature of the unusual casing, imagining what sea creature had dwelled inside before the shell had been emptied of its tenant to travel alone with the tides. Tracing my fingers around its curved rim a final time, I returned the shell to the shore and carried on.
That evening, back at the dive center I was staying at on the Indonesian island of Bangka, I noticed an identical set of shells huddled together on a shelf. Cradling one of them to a table, where a pair of divers sat recording logbook notes from their day’s descents, I asked the men if they knew what it was. “It’s a nautilus shell,” they replied simultaneously, each then pinning a tantalising note to the name. “They’re really unusual to find,” said the first. “And nautiluses are these really old creatures that live at incredible depths,” added the other.
The following morning I walked the pale shore with little hope of finding the shell again. The midnight tide had been wild and high enough to strand a life jacket stamped TOKYO in the arms of a tree. Lines of wrack spelled out a ragged new message from the deeps and the mangrove swamp burbled with treacly brown water and scuttling crabs. In all probability the shell had risen with the tide, rolling in the foaming waves until it was steered out to sea like a lone coracle for potentially hundreds of nautical miles, adrift in its seemingly endless blue realm once more. But only meters from the marooned life vest, and so near the spot where I’d left it that I couldn’t be certain it had shifted at all in the night, shone not one but two nautilus shells in the steepling light of the island.
I placed the shells close together on the sand: the pairing of their paths was a timely reminder that there are always two ways into wonder. One route is coined through connection, beauty, immediacy, mystery, and surprise; the other is forged through the act of naming, the enlarging vista a word or two might potentially reveal about another form of life, all the remarkable intricacies and complex adaptations of a singular wild existence made suddenly approachable. What I’d thought of as empty was beginning to brim. And it was the compound possibilities of this process, the way—according to the Scottish writer and alpinist Nan Shepherd—a “thing to be known grows with the knowing,” that had sent me back along the shore that morning.
And what we know about the nautilus is this: that, as a species, it’s unfathomably old. Often referred to as a living fossil, a description first employed by Charles Darwin in 1859, the nautilus has remained, in evolutionary terms, essentially unchanged for some 500 million years of existence, joining the esteemed and antique company of the horseshoe crab, coelacanth, and elephant shark as an exemplar of endurance. Though when I posted a photo of the nautilus shells on Twitter, remarking on the extraordinary longevity of their kind, I received a reply that said, “Not living fossils! Lose ten points.” Accompanying the tweet was an article, written by the author of the reply, which vehemently argued against the use of the term. While the piece was unquestionably of interest, its author presumed an inherently constrictive meaning of living fossil. He saw it as conjuring a pejorative image of animals he felt were essentially “anachronistic” in the historical record, creatures perceived to be “simply hanging on in there and lonesome, rather than modern, flourishing organisms.” Perhaps some echo of our high-speed and digitally streamed age can be picked up in this particular phrasal interpretation, an era infatuated, particularly when it comes to adaptations of technological design, with the perpetual reinvention and newness of things. A time when the old appears to have lost some of its shine.
Instead of the archaic and antiquated, though, the notion of living fossils frames for many a very different view. It evokes a picture of persistence, durability, and biological distinctiveness—it conjures an image of resilience. To have been witness to so many turbulent environmental changes over the course of 500 million years, tectonic in their scale and consequences, without having the need to radically recalibrate one’s evolutionary course is surely a testament to the quality of a creature’s tenacity and the admirable characteristics of its definitive design. Thriving long before the planet’s continents began to shift into their present configuration, the nautilus would have been considered ancient even when dinosaurs first roamed the world.
A large mollusc of the cephalopod family—which includes the octopus and squid, and is so named because its members’ feet are attached to their heads—this particular species of nautilus, the chambered nautilus, waves a fan of up to 90 pale and ethereal tentacles from the forward aperture of its shell, sifting the pelagic waters for shrimp, fish, and small crustaceans that are pulled irrevocably towards a powerful, parrot-like beak. When desiring to move forwards, backwards, or even laterally, the nautilus utilizes a built-in propulsion system, encouraging water into the mantle cavity within its shell and then jetting it outwards through a flexible, directional funnel. During the day, the creature stays clear of predators by sinking to depths that can reach 2,600 feet. And there, in the aphotic abyss, two and a half times deeper than the deepest scuba descent ever recorded, it withstands the kind of intense water pressure that would instantly collapse human body tissues and vital organs, migrating upwards through the murky night sea to feed alongside shallower coral reefs under cover of darkness. And it was this columnar movement and ability to exist under intense pressure, together with the chambered nautilus’s ability to control its underwater buoyancy, which led me to the most remarkable surprise of all.
It had been Simon Foote’s idea to split one of the shells in two. Running the dive center I was staying at, Simon wanted to understand what we’d read about online the night before when I showed him my finds: the elegant engineering at the heart of the nautilus’s existence. Born with its shell already attached, the nautilus is entirely reliant on that tiny initial coil and its four internal chambers from the moment it enters the world. These compartments—linked together by a thread of organic material called a siphuncle, which passes from the nautilus’s body through each of the otherwise sealed cavities—contain a carefully balanced blend of saline liquid and gases, a composition that the animal is able to alter the ratio of through the injection or expulsion of these materials via the siphuncle in accordance with the external pressure of the sea, acting effectively as ballast tanks, used to attain positive, neutral, or negative buoyancy depending on the nautilus’s needs. And as the sea creature grows, so too do the number of chambers, each new addition incrementally larger than the last. Always housed in the most recent of its built abodes, an adult nautilus can carry as many as 38 of these defining compartments within the coiled confines of its casing.
Simon placed the shell in the grip of his vice, tipped his googles down and started up an angle-grinder.
He pressed the starter button again.
After checking the cable and socket for a loose connection, he removed his googles. “There’s always something that stops working in this heat,” he sighed.
I was disappointed we’d failed so early in the attempt, but not Simon. An engineer by training, he simply took the setback in stride and devoted his thoughts to other possibilities, as though without an obstacle it wouldn’t have been a fair challenge. “I took apart my first engine at the age of eight with my grandfather,” he said, ingenuity not solely the preserve of the sea’s living fossils. “And I’ve had about 32 bikes since then. It’s how I funded my degree. I’d look for old bikes on eBay, usually something with collectable appeal, buy them, and then do them up.” He removed the long, thin blade of a worn hacksaw, wrapped bands of electrical tape around his fingers like a boxer before a fight, and lined up a route to follow on the perimeter of the housing. He then began gently sawing through the dense walls of the shell, puffs of pale dust rising when he blew each incision clean, rotating the nautilus shell through either the clasps of the vice or in the palm of his hand. After almost an hour of careful and laborious cutting, sweat steadily beading on his skin in the midday tropical heat, he raised his eyebrows in mock alarm. “This is the moment,” he said.
While it was René Descartes who first described the logarithmic spiral, it was the Swiss mathematician, Jacob Bernoulli, who would later devote such considerable time to its qualities that his name for it, Spira mirabilis, or the miraculous spiral, came to adhere to the shape. Bernoulli was drawn in particular to one of its fascinating mathematical properties, revealed in stunning clarity when Simon finally pulled the shell apart like a chocolate Easter egg split open along its seam. From those tiniest chambers at the beginning of the coil, where the nautilus was tethered at birth, the logarithmic spiral of its shell enlarges through successive windings while remaining constant in relation to earlier turnings, a process known as self-similarity. As it spins larger and larger the spiral retains the same ratio as that at its inception. And by the time it opens like a great funnel at its widest and final aperture, where the living nautilus would have last been attached, having moved house throughout its life into the most recently added room as it grew, each successive turn in the spiral exists in refined, geometric progression. Unlike the Archimedean spiral, recognisable from a mosquito coil placed upon the floor, which remains the same size and profile throughout each of its curves, the logarithmic spiral is immediately distinguished by its appearance in other natural forms, sharing the same elegant shape as a swirling tropical cyclone, the ancient fossils of extinct ammonites, and the extended arms of spiral galaxies.
Simon blew dust from one of the half shells, turning it in his hands so that the afternoon light entered the individual chambers, as if rooms that had been closed and curtained for years were suddenly opened once more. Seeing inside was a revelation, each compartment clearly demarcated and the connecting portals which the siphuncle had once threaded visible at the centre of the successive walls called septums. For such a small dwelling, the resplendent complexity of its architecture was unimaginably elaborate and astonishingly beautiful too. It had achieved the radiant gracefulness of wild restraint.
For Jacob Bernoulli, this sophisticated spiral had led to philosophical considerations of both matter and spirit. He saw it as a symbol of the “resurrection of our flesh after various changes and at length after death itself.” Bernoulli even made arrangements for his headstone to be carved for posterity with a Spira mirabilis alongside the Latin phrase Eadem mutate resurgo, having glimpsed in the nautilus’s shape affirmation that would guide him forward through his material finality: “Although changed, I shall arise the same.” In his later years he felt profoundly encouraged by this faithfulness of essence, and although a mathematician and religious adherent rather than a naturalist, ascribing to the logarithmic spiral’s geometric perfection the sacred ascension of the spirit, I’ve yet to discover a more striking and accurate appraisal of the quality of living fossils than his description of undying fidelity to form: “Because our miraculous curve always in its changes remains constantly the same and identical in type, it can be regarded as the symbol of fortitude and constancy in adversity.”
The sea was changing when Simon and I left his workshop. Not only in easily perceivable tints, a grey skim of cloud darkening the cobalt surface to the color of a bruise, but also, less visibly, from within. As with all seas on the planet—from the coldest polar deeps to the warmest tropical shallows—it was undergoing an inner transformation, but unlike the logarithmic spiral this change would leave the sea’s essence fundamentally altered rather than the same. It wouldn’t rise with the tide as before. As carbon dioxide is dumped in accelerating amounts into the atmosphere through the burning of fossil fuels—that alchemical conversion of ancient stores of sunlight in the form of decomposed plant matter to potent reservoirs of energy—more and more of it is dissolving in the world’s waters, where roughly 30 to 40 percent of all carbon emissions end up. And once absorbed, this intensifying concentration is gradually acidifying the seas, lowering the water’s pH level to such a degree that it makes life increasingly difficult for the nautilus.
For the 500 million years that the animal has existed in a largely unaltered state, enduring the adversity of the sea’s historic changes—including rising and falling water levels and a period of intense climatic heating some 55 and a half million years ago—the nautilus has been entirely reliant on the presence of free carbonate ions in the ocean to construct that complex spiralling structure at the core of its continuing existence, a dependence shared with such other calcifying creatures as coral, oysters, sea urchins, and clams. But the injection of colossal volumes of carbon dioxide into the planet’s seas has triggered a series of chemical changes that are reducing the concentration of these ions, thereby lessening the saturation level of calcium carbonate in the water and impairing the ability of these wild animals to assemble and maintain their mobile homes. Studies of other mollusc species have even revealed that ocean acidification is responsible for wearing away those shells already built, rubbing them thinner by the day, slowly dissolving their constituent chemical compounds and elements back into their natal, yet changing, sea.
I set one of the half shells down on the sand, its concealed radiance open to the air. Despite all that I’d learned of its lasting shape, uncertainty was now the enigma at the heart of the shell: having outlived five mass planetary extinctions, the nautilus is at risk from the sixth. Along with the volatile turbulence of the seas, it faces the mounting pressure of illegal poaching for the ornamental shell trade; it faces the firing line of our deeds and desires. And if in the coming years, decades, or even centuries it is to finally depart this world, taking with it to the grave all its encoded memories of ancient waters and waves, where it once co-existed with sea creatures so radically different to those present today that many would seem to us to be purely imaginary in form, then the nautilus will have disappeared in the briefest blink of a geological eye, its reign of nearly unrivalled persistence in a largely stable state undone not by some fatal flaw in its evolutionary design but by the short-term ambitions and endeavors of humankind. The active adjective that makes it unique as a living fossil would suddenly be dropped, so that it became merely a dead noun in name, a reminder, like all fossils, of things once here that are no longer animate or part of this world.
Perhaps, long ago, this possible future had already been foreseen, but rather than deciphering it as a message we chose to regard it as a mistake, for in 1705, in Basel, Switzerland, the stonemasons tasked with etching the nautilus’s logarithmic spiral on Jacob Bernoulli’s grave as the enduring symbol of “fortitude and constancy in adversity” chiselled the far less remarkable Archimedean spiral instead. And through their labors they gave warning: unless our course is altered, it is we who will unwind the miraculous spiral of the sea.