It is a flattened, burrowing sea urchin found in the north-eastern Pacific Ocean from Alaska to Baja California.

Their body is covered with fine, spiny tube-like feet with cilia, and like other echinoderms they have five-fold radial symmetry.

The tube feet are arranged in five paired rows and are found on the ambulacra—the five radial areas on the undersurface of the animal, and are used for locomotion, feeding, and respiration.

They are either found subtidally in bays or open coastal areas or in the low intertidal zone on sandy on the Northeast Pacific coast.

Like its cousins, dendraster is a suspension feeder which feeds on crustacean larvae, small copepods, diatoms, plankton, and detritus.

When feeding they usually lay at an angle with their anterior end buried and catch small prey and algae with its pedicellariae, tube feet, and spines and pass them to the mouth.

In high currents adults grow heavier skeletons while juveniles swallow heavy sand grains to keep from being swept away.

This particular species of sand dollar is known for its curious behavior: When exposed to a steady flow of water, they gather in groups, forming aligned rows in the sand, while digging their front edge in and raising their back edge into the flow of water, lined up so it passes from right to left across their bodies.

This is one reason they are believed to live in large groups and tend to release gametes at the same time into the water column.

Predators include the seastar Pisaster brevispinus and the starry flounder Platichthys stellatus as well as crabs and sea gulls.

[3] Large storms or high temperatures and desiccation can cause mass mortality if low tide coincides with a hot midday and the animals are exposed to air for just 2 to 3 hours or washed up and buried in the sand.