A large oval limpet with 20 strongly sculptured ribs with weaker ribs in between. It is usually dark green or orange/brown to black with lighter spots and streaks.

Found on rocks in mid to low tide zone, often associated with the modest barnacle. Found from Otago, south, but most common in the Subantarctic Islands.

Grazes on algae on the rocks.

NZ Coastal Marine Invertebrates; Vol 1