Lutraria is a genus of medium-sized marine bivalve mollusks or clams, commonly known as otter shells.

The shell is fairly thick and is sculptured with fine concentric lines corresponding to periods of growth.

[2] These mollusks live buried in sand to a depth of about 30 cm (12 in), usually below low water mark, with their siphons extended to the sea bed.

[3] Fossils of Lutraria are found in marine strata from the Eocene to the Quaternary (age range: from 33.9 to 0.0 million years ago.).

Fossils are known from Europe, South Africa, Japan, New Zealand, Pakistan, Australia, India and Argentina.