Grows to about 100mm

Restricted to New Zealand, but is a sub- species of the European edible blue mussel M. edulis which is widely distributed in cool temperate inter-tidal waters of both northern and southern hemispheres. Dark blue-black shell, often chalky white around the hinge area. Abundant around and south of Cook Strait; isolated populations on North island east coast. Naturally occurs in the upper areas of the inter-tidal zone.