Book 24, Question 115
How can solid rock be made of tiny shells?
Limestone is a rock made mostly from the shells and skeletons of sea creatures, such as corals, clams, and tiny plankton. They piled up on the seafloor for millions of years and were pressed into stone. Many limestone blocks contain fossils you can see. Tyndall stone from Manitoba, used in many buildings, is full of ancient sea animals.