This past month, I found myself exploring the western edge of central Vancouver Island—the traditional, unceded territory of the Kʼómoks First Nation.
This is a land where the forest meets the sea in a symphony of cedar, fir, and arbutus, their driftwood limbs worn smooth by the relentless rhythm of Pacific waves.
It’s easy to see why people have called this rugged coastline home for millennia.
These are nature’s souvenirs, tokens of geologic and biological processes that have been shaping our planet for hundreds of millions of years. My own home, a small shrine to these curiosities, features several abalone shells that now serve as nacre dishes for ceremony and collections of beach-found beauty.
In a more natural setting, decaying bone absorbs calcium carbonate from surrounding shells.
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Abalones descend from ancient archaeogastropods, an early and primitive lineage of marine snails.
But shells are far more than decoration. In coastal archaeology, they tell a story—of diet, settlement, and preservation. For countless generations, Indigenous coastal communities left behind shell middens—accumulations of discarded shells, bones, and other remnants of daily life. Far from simple refuse, these middens are time capsules.
As the shells break down, calcium carbonate (CaCO₃) leaches into the surrounding material, creating an alkaline environment that slows decay and can “embalm” organic matter like bone and antler. This remarkable natural chemistry is one reason we know so much about early toolmaking traditions—antler needles, for instance, survive beautifully in such conditions.
Fun fact: calcium carbonate is one of Earth’s most abundant compounds, forming chalk, limestone, and marble. It’s the same substance that makes up seashells, coral skeletons, and even the exoskeletons of tiny marine plankton. In chemistry, CaCO₃ is a mild base—it neutralizes acids, which is why it’s found in antacids like Tums.
When exposed to stronger acids, it reacts to release carbon dioxide, as in the reaction:
CaCO₃(s) + 2HCl(aq) → CaCl₂(aq) + CO₂(g) + H₂O(l)
At high heat (above 840°C), calcium carbonate decomposes into quicklime (CaO) and carbon dioxide—a reaction used for thousands of years in lime kilns.
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| Comox Foreshore, Kʼómoks First Nation / Photo: Kat Frank |
The process gradually replaces the bone’s original organic components, strengthening it and making it more resistant to decay—a miniature version of fossilization.
Over centuries, the shells even enrich the soil, increasing alkalinity and preserving a record of meals, tools, and lives once lived along these shores.
Abalone have a surprisingly ancient and fascinating lineage in the fossil record! These marine gastropods belong to the genus Haliotis, within the family Haliotidae, and are part of the larger molluscan class Gastropoda—the same great evolutionary family that includes snails, limpets, and whelks.
The oldest confirmed Haliotis fossils appear in rocks from the Cretaceous, roughly 100 to 70 million years ago. Fossils have been found in marine deposits in places such as Europe, Japan, California, and New Zealand, showing that by the Late Cretaceous, abalones were already widely distributed across the world’s shallow coastal seas.
Their distinctive ear-shaped shells and the characteristic row of respiratory holes (used for breathing and expelling waste) make them relatively easy to identify in the fossil record. While the earliest fossil abalone were generally smaller and less ornamented than modern species, their overall body plan hasn’t changed much—a testament to a highly successful design.
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Over millions of years, they specialized for life clinging to rocky shorelines, developing their broad, muscular “foot” and strong grip to withstand crashing surf.
Their shell structure—a mix of aragonite and protein arranged in microscopic tiles—became one of the toughest biological materials known, inspiring modern materials science.
Because abalone shells are made of nacre (mother-of-pearl), they fossilize beautifully when conditions are right, sometimes preserving their iridescence even after tens of millions of years.
That shimmering interior you see in a beach-found abalone shell? It’s built of the same mineral layers that have been dazzling paleontologists since the age of the dinosaurs.
The photo of shells from Comox, shared here by my cousin Kat Frank of the Kʼómoks First Nation, captures that same enduring beauty—a reminder that science, art, and culture are all written in the language of nature’s chemistry.