As its name suggests, the common sand dollar resembles a large coin and doesn’t have the five arms that other echinoderms have. Its body is shaped like a flat disc and it ranges in colour from reddish to purple-brown. The topside is darker than the underside.
The test, the name given to the sand dollar’s rigid skeleton, has small, symmetric perforations shaped like petals. The test is also covered in miniscule spines, which sand dollars use to move about and even burrow into the sand.
The test also has small holes through which protrude little tube-feet, similar to those of starfish and sea urchins. It is these tube-feet that allow a sand dollar to move about.
In addition to its small spines, the surface of its body is covered in small pincer-like structures that it uses to clean its surface and rid itself of any parasites.
This marine animal’s mouth is located in the middle of the underside of its body. It has five small teeth that point toward the center.