What Sedimentary Rock Forms Underwater from Animal Shells?
The answer is limestone.
How Limestone Forms
Formation: Limestone primarily accumulates from the calcium carbonate (CaCO3) shells and skeletons of marine organisms, including corals, mollusks, foraminifera, and algae.
Process: Over time, these shells and skeletons pile up on the ocean floor, compact, and cement together to form limestone.
Other sources: While most limestone is biogenic, some forms through chemical precipitation or the buildup of other carbonate materials.