Sand dollars have five teeth inside them. When broken open, the teeth fall out and are shaped like doves, giving them a legendary meaning.
Sand dollars are flattened, burrowing sea urchins related to sea cucumbers and starfish. The sand dollar's exoskeleton, or test, is made up of calcium carbonate plates arranged in a circular pattern and is covered with a velvety mat and spines with tiny hairs called cilia. These cilia help the animal to move or burrow into the sand and to ferry food into its mouth, located on the underside. Inside the mouth, the sand dollar has a set of five teeth, which produces the rattling sound when the test is shaken.
The Legend of the Sand Dollar is an Easter and Christmas favorite. This story tells of five doves that are inside the sand dollar that, when broken open, spread goodwill and peace.