These Enchanting and Colorful Photos of Seashells and the Mollusks Who Create Them Will Have You Marveling at the Natural World

A seashell is the story of a creature’s life, written line by line. Soft-bodied mollusks protect themselves with crystals of calcium carbonate, adding new layers as they grow. The bands and ridges may reveal changing seasons, diets and life cycles.

The shells’ many shapes also reflect how different species have evolved over the 500 million years since mollusks first appeared. Back then, their shells were simple caps and coils. Today’s mollusks include fanlike scallops, spiny conchs and spiraled nautiluses.

Yet most people who pick up shells on the beach don’t give much thought to the animals that made them. Leal reminds museumgoers that shells aren’t simply formed by the elements the way rocks are. A mollusk absorbs calcium and carbon from the water and fuses the molecules together, generating a rocklike material out of a body part called a mantle.

Bivalves—such as clams, oysters, mussels and scallops—encase themselves between two hinged shells. Sea snails build a single swirling shell that resembles the top of a soft-serve ice cream cone. How do these creatures produce such a range of colors and patterns?

The colors are part of a protein matrix that binds the crystals together. Leal’s colleague Suzanne Williams, at the Natural History Museum in London, has studied the pigments—pink and yellow porphyrins, brown and black melanins, orangy carotenoids—and found that certain genes switch the production of certain colors on and off, making dots or stripes. Patterns may help an animal camouflage.

But many sand-dwelling mollusks have spotted shells that make them stand out, not blend in. Distinct patterns may help creatures of the same species recognize one another, but mollusks have poor color vision. By the time people find seashells on the beach, they’re usually empty.