Quite a large mollusc with a circular body and a well-developed body split by a mid anterior cleft. The body is protected by a flattened oval shell which is considerably smaller than the animal itself. The upper part of the body is covered with uneven tubercles and tubular rhinophoral tentacles extend out from beneath the shell. The radula is very broad with many small rasping teeth. The shell is an off-white colour while the mollusc is orange or brown with white tubercles, and an orange bordered off-white mantle.
The species feeds at night and prefers to remain well hidden in the sediment during the day. Mating takes place between August and March and the eggs, wrapped in a light orange coloured ribbon are deposited in a circle. The Mediterranean sea slug feeds mainly on sponges.