Seashells come in an astounding variety. Some are curved and round, others long and tube-like. Some are smooth, others bumpy. Some are large, others small. Plus, they come in a rainbow of colors: red, green, brown, purple, pink, and more.

All that variety comes from the same source: little animals called mollusks, with a mighty muscle called a mantle.

Richelle Tanner.
Tanner

I found out all about them from my friend Richelle Tanner, a postdoctoral research associate in biological sciences at Washington State University. She is very curious about the ocean and knows a lot about mollusks, a type of animal with a soft, moist body.

Unlike humans, cats, and other animals with backbones, mollusks don’t have skeletons inside. Many move through life with just their soft bodies. But some grow shells for protection, as a kind of traveling armor.

That’s where seashells come from, Tanner explained. “A seashell is a protective outer coating secreted by the animal’s mantle, which is one of their muscles,” she said. The mantle forms the soft outer wall of their body.

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Dr. Universe