Live sand dollars are animals that are related to sea urchins, sea stars and sea cucumbers.
When sand dollars are alive they can look like a cookie with fuzz all over it. The fuzz is a sand dollar's many spines that help it move along the shallow sand under water. This is how it hunts for food like crustacean larvae and algae.
From the Monterey Bay Aquarium:
Cool FactsThe sand dollar’s mouth has a jaw with five teeth-like sections to grind up tiny plants and animals. Sometimes a sand dollar “chews” its food for fifteen minutes before swallowing. It can take two days for the food to digest.
Scientists can age a sand dollar by counting the growth rings on the plates of the exoskeleton. Sand dollars usually live six to 10 years.
California sheepheads, starry flounders and large pink sea stars prey on sand dollars. When threatened by pink sea stars, sand dollars bury themselves under the sand. Observers have seen a pink sea star leave a wide path of buried sand dollars as it moves across a sand dollar bed.