Shells that tell a story: Dr. Dinazard Raheem on Sri Lanka’s Ancient and Endangered Snails

At first glance, a snail's shell might seem like nothing more than a spiral of silence — a tiny relic abandoned on the forest floor. But for Dr. Dinazard Raheem, these delicate coils hold the story of an island's past, its changing climate, and perhaps even its future.

- BY IFHAM NIZAM

Addressing the Nations Trust—Wildlife and Nature Protection Society (WNPS) recent monthly lecture held at the BMICH, Dr. Raheem, one of Sri Lanka’s leading malacologists, took her audience on an extraordinary journey — from the island’s misty montane forests to the fossil beds of ancient continents — tracing the hidden history and fragile survival of land snails.

“Something that is really useful about snails,” she explained, “is that they have this calcium carbonate shell, which remains in the environment long after the animal has died. These shells are incredibly powerful tools — they allow us to detect species even when the live snails aren’t active.”

When the weather dries up, live snails retreat into the soil, vanishing without a trace. But their shells endure, sometimes for decades. “You can still detect the presence of a species in a place simply because you've found its shell,” she said, showing slides of shells in various stages of decay — from freshly dead to almost crystalline. “By the time you see that internal structure, the calcium carbonate superstructure, you're literally looking at the architecture of time.”

Fossils in Amber and the Story of Gondwana

Land snails, Dr. Raheem explained, are far from humble creatures of the undergrowth. They are evolutionary timekeepers. “Unlike many other animal groups, some land snail families have incredibly rich fossil records,” she noted. “Tn Sri Lanka, the Cyclophoridians are a great example — a group represented here by living species, but whose fossils go back millions of years.”