The toheroa is a very large shellfish with a solid white, elongated shell with the apex at the middle. Maximum length is 117 mm, height 81 mm, and thickness 38 mm.
It is found in both the North and South Islands, but the main habitat is the west coast of the North Island. The best grounds are wide fine-sand beaches where there are extensive sand-dunes, enclosing freshwater, which percolates to the sea, there promoting the growth of diatoms and plankton generally.
Not well understood. The subject of ongoing work.
Coastal Marine Inverts Vol 1