Eccentric sand dollar (Dendraster excentricus), also known as the sea-cake, biscuit-urchin, western sand dollar, or Pacific sand dollar, is a member of the order Clypeasteroida, better known as sand dollars, a species of flattened, burrowing sea urchins found along the Pacific Ocean from Alaska to Baja California. Dendraster excentricus is an irregular echinoid that is flattened and burrows into the sand, unlike the regular echinoids,or sea urchins. It can be found living in the Pacific Ocean from Alaska to Baja California.The range for Dendraster excentricus is larger and includes the range of the other two extant species of Dendraster: D. vizcainoensis and D. terminalis. The flower pattern in this species is off-center, giving it the species name excentricus.
They are either found subtidally in bays or open coastal areas or in the low intertidal zone on sandy on the Northeast Pacific coast. It can live at a depth of 40 to 90 meters, but usually is found in more shallow areas. Sand dollars are usually crowded together over an area half buried in the sand. As many as 625 sand dollars can live in one square yard (0.85 sq m). It is the only sand dollar found in Oregon and Washington.
Monterey Bay Aquarium