Nihonia circumstrictaNihonia circumstricta is a species of sea snail, a marine gastropod mollusk in the family Cochlespiridae.DescriptionThe length of the shell varies between 50 mm and 65 mm, its diameter between 15.5 mm and 19 mm. The shell has an elongate-fusiform shape. It contains 9 weakly angulate whorls.DistributionThis species occurs in the Indian Ocean off Tanzania at depths between 300–400 m.