shells | Ask Dr. Universe | Washington State University

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How do turtles get their shells? – Malachi, 8, New York

July 23, 2025 melissamayer

Dear Malachi,

Sometimes animated turtles seem to live inside their shells like it’s a tiny home. They may even hop out of the shell and run around.

That’s funny in cartoons and games, but my friend Ryan Wagner told me it could never happen in real life. He’s a wildlife biologist at Washington State University. He studies animals like turtles and frogs.

It turns out that a turtle’s shell doesn’t sit on top of its body. It’s part of the turtle’s body.

“Turtles are their shells,” Wagner said. “The shell is made up of their bones. As the turtle grows, its shell … » More …

How are seashells formed? And why are they different colors? Can seashells live or die? - Caroline, 9, Crestwood, Ky.

February 28, 2020 jaime.chambers

Dear Caroline,

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.

I found out all about them from my friend Richelle Tanner, a scientist 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.

If mollusks have such heavy shells to drag around with them, how have they spread all over the ocean? -Michel W.

August 10, 2015 rcwebber

Dear Michel,

Mollusks, from land snails and slugs to oysters and mussels in the sea, have a few things in common. They have a head. They have a soft middle part that holds their organs. Then, some have a muscle that’s known as a “foot.”