Almost circular with rounded whorls. Upper surface is smooth and covered by a light brown periostracum (skin), which can wear away to show a smooth purple tinged shell. There is an internal shelf on the underside which hides the spire.

Found on rocks, often attached on or inside dead shells.

Grazer.

Coastal Marine Inverts Vol 1
Photo Credit: Rod Morris. Photos available from www.rodmorris.co.nz