How are sand dollars created and what is the process behind their formation?

Sand dollars are marine animals that belong to the echinoderm family. They are formed through a process called metamorphosis. Initially, sand dollars start as larvae in the water, and as they grow, they develop a hard exoskeleton made of calcium carbonate. This exoskeleton eventually becomes the familiar round, flat shape we associate with sand dollars. Over time, the sand dollar's body adapts to its environment, allowing it to burrow into the sand and feed on small particles.