These shells vary in size and shape, as the name refers to a number of different families. ‘True’ Periwinkles are squat, while nerites are more rounded and Turban Shells are conical. The shells are often rough or ridged with a circular opening, and always have an operculum, the protective flap covering the opening.
They are found right around the Australian coast in intertidal zones and around shallow reefs, usually to depths of about 20m; Turban Shells are found on the bottom of pools on weed-covered intertidal reefs. Periwinkles are harvested by hand from the Wild and Turban Shells are harvested by divers off eastern Tasmania. Trochus Shells are also included under the general name Periwinkle.