The periwinkle has a conical shell with a white background and blue stripe, however, the colour may be eroded off.

Abundant on rocky shores at or above the high intertidal zone. Found in harbours through to exposed coastlines where it can be living in the splash zone.

Grazes on thin films of seaweed and lichen.

Older individuals live occur higher up the shore and juveniles shelter inside empty barnacle shells. Was Nodilittorina antipodum

NZ Coastal Marine Invertebrates; Vol 1