The surface is covered with sharp white or mauve spines, each surrounded by a ring of pedicellariae, tiny pincer-like organs.

[3][4] The rainbow star is found in northern parts of the Pacific Ocean with its range extending from California to Alaska at depths down to about 250 metres (820 ft).

[3] The rainbow star is a predator and feeds on a range of invertebrates including gastropod molluscs, limpets, bivalves, brachiopods, chitons, barnacles and tunicates.

[5] It can dig up clams buried in the substrate and force the valves apart with the suction provided by its tube feet.

It then everts part of its stomach, thrusting a fold inside the bivalve and excreting digestive enzymes onto the tissues.