Flattened in structure and covered in spirally arranged nodules.

Common on northern semi and exposed coastlines. Often found under boulders.

It feeds on the microalagal films which cover the surfaces of rocks and on seaweed. Animal material such as sponges, bryozoans or hydroids may also be eaten.

Part of a large group of snails found around the world. The large tropical Pacific species is harvested commercially to make pearly buttons from the shell.

NZ Coastal Marine Invertebrates; Vol 1