It has a pointed tip, with only a few hinge teeth. The shell is very dark blue to blue-black.

Mid to low intertidal on moderate to exposed rocky shores. Very common in some parts of South Island (eg Marlborough Sounds) and less common in North Island.

Filter feeder.

The adductor mussel holding the two shells together is not as strong as the Green-shelled Mussel - may be easier prey for predators. Competition is fierce on the shore and if one mussel dies or is removed, the surrounding mussels will quickly grow to fill its place. This helps to ensure the integrity of the bed. Attached to rocks by byssus threads, a remarkable adhesive that is neither degraded nor deformed by water, as are synthetic adhesives.
Daily Limit per person, South east and Stewart Island, 50, Southland 25, no minimum size.

NZ Coastal Marine Invertebrates; Vol 1