The sedimentary rock formed by deposits of shell fragments is called coquina.

Here's why:

* Coquina is a type of limestone.

* It's made up of loosely cemented shell fragments, often from marine organisms like clams, oysters, and snails.

* The fragments can be small or large, and the rock's texture can be coarse or fine.

* Coquina often forms in shallow, warm water environments where organisms thrive.

Let me know if you have any other questions about rocks!