This large seastar has 8-16 rays (usually 11-12) and no pedicellariae. Paxillae on the aboral surface are separated from each other by about their diameter and blunt (photo), so that the dorsal surface is rather smooth. The ambulacral grooves have enlarged marginal plates along their margins. Disk diameter is about 1/3 total diameter and the aboral surface does not have a prominent gray-blue streak radiating from the central disk and out each ray (but see photo below). Rays taper gradually from base to tip. Aboral surface usually brown or or grayish, but may be orange or mottled. Diameter to 40 cm.