The shell is large, globular and slate grey to black with indistinct spiral lines. The interior is iridescent green to pink.

Found at mid to high tide levels on and under rocks, in crevices, and around the edges of rock pools of shores with low to moderate wave action.

It feeds by scraping algae from rocks and beach cast plants. It is eaten by larger predatory whelks.

It will move quickly away when exposed to sunlight.

NZ Coastal Invertebrates; Vol 1 Guide to Common Intertidal Species of the South Island
Photo Credit: Rod Morris. Photos available from www.rodmorris.co.nz