The most distinctive feature of this species appears to be the bright blue, or white spot on the upper side of each ceras. The spot is sometimes surrounded by a dark green ring. Ther can be a similar mark behind the eyes in the dorsal midline, but this can lack the ring, and be reddish in colour. A reddish subapical band can also be present on the cerata.
Size to about 10 mm. this species is found on the fan algae Avrainvillea.