On the ventral side, tube feet, purple in color (or pale, transparent pink), are arranged in rows on each arm.

Most horned sea stars found are a roughly rigid five-pointed star-shape with tapering arms to the end, although there are anomalies like four or six-armed specimens; they may grow up to 30 cm (12 in) in diameter.

This coloration, combined with the small horns on its dorsal side, give the sea star an appearance similar to a chocolate chip cookie.

Field studies suggest the species could be restricted to the western Pacific Ocean (Thailand to Samoa and Japan to New Caledonia).

Horned sea stars are opportunistic carnivores; adults are known to prey on most sessile life forms including hard corals and sponges in an aquarium.