Obesotoma simplex is a species of sea snail, a marine gastropod mollusk in the family Mangeliidae.
The length of the shell varies between 7 mm and 20 mm.
The shell is whitish or flesh-white, under a livid olivaceous epidermis. It is smooth, or with fine spiral striae. The aperture is violaceous to white.
This species occurs in European waters and in the Northwest Atlantic Ocean off Svalbard and in the Barents Sea; also in the Bering Strait and in the Sea of Okhotsk
