Paphies subtriangulata is a species of edible bivalve clam known as tuatua in the Māori language, a member of the family Mesodesmatidae and endemic to New Zealand.

It is found on all three of the main New Zealand islands, buried in fine clean sand on ocean beaches.

Its closest relative, the pipi (Paphies australis), has a symmetrical shell.

The soft parts of the animal are an edible delicacy, made into fritters or boiled and served on the shell.

The clam burrows beneath the sand, and does so very quickly, making it a challenge to dig for at times.