How are seashells created? Or any other shell, such as a snail's or a turtle's?

Seashell - Wikipedia

Turtle sea snail hi-res stock photography and images - Alamy

PPT - The Effects of Acids on Seashell Corrosion PowerPoint

Where do sea shells come from, and how are they made? - Quora

Closeup Texture Of Snail Shells Examining The Intricate Background

The Magick of Seashells

Article Archives • Turtle Conservation Society of Malaysia

Is the shell on a turtle and snail made of the same material? - Quora

Seashell - Wikipedia

How are seashells made? - Woods Hole Oceanographic Institution

Why do seashells wash up on the shore? - Quora

Did anyone else accidentally surround themselves with mostly 1 type? : r/Enneagram

Seashells of Snail, Clam, Shellfish and Conch Stock Vector

Full article: Clarifying 'carbon sequestration