Gigantidas tangaroa

Gigantidas tangaroa is a species of deep-sea mussel, a marine bivalve mollusk in the family Mytilidae, the mussels.

Habitat
This species was first described from northern New Zealand, from seeps off Cape Turnagain and Cape Kidnappers at a depth of 920 to 1205 m.

Description
The shell  of this species is large, up to 200 mm long, showing external dull white growth lines. Its anterior margin is narrow but evenly rounded. Its posterior margin is convex dorsally, its posterior angulation well-defined, situated above the posterior adductor scar. Its periostracum is thick, hard and a dark brown colour. Its anterior adductor scar is short, and its pallial line curves parallel to its ventral margin.