[1] The type specimen was collected on a sandy bottom, 10 fathoms (18 m) deep, near the mouth of San Francisco Bay.

While a row of spines generally runs along the top of each arm, they are otherwise scattered across the animal in no particular pattern singly or in clumps of two or three.

[3] On the lower, or oral side of the star, deep grooves radiate from the mouth which contain four rows of tube feet.

The tube feet around the mouth are particularly long, at least equal to the radius of the central disc, to aid in digging prey from the sea bottom.

[3][5] This sea star occurs along the coast of North America from Sitka, Alaska to La Jolla, California.

[6] The pink sea star is found in relatively shallow water from the lower intertidal zone to 110 metres (360 ft) deep.

[7] It is thought that groups of stars use environmental signals to coordinate spawning to increase the chances of fertilization.

Towards the end of the last stage the larva develops a large sack like structure, a primordium, and begins searching for a suitable surface on which to settle.

[8] It is a slow-motion hunter; it may take it several days to dig its prey from the sediment, latch on to it with its tube feet, and pull the valves open.

The pink sea star secretes digestive fluids and eats the bivalve inside its own shell.

It will eat sand dollars, snails, including Kellet's whelk,[7] barnacles, polychaete worms, and small Dungeness crabs.