Isognomon perna

Isognomon perna, the brown purse shell or rayed tree oyster, is a bivalve in the family Isognomonidae common in the Indo-Pacific including Hawaii.

Description
Isognoma perna colors range from a brown or light-yellow purse shell to beige with a brown striped pattern and resembles a miniature clam.

Distribution
Commonly found in the Indo-Pacific, including Hawaii, Western Polynesia, Eastern Polynesia, North to Japan Eastern to Southern Africa, New Caledonia, and Society Islands.

Habitat
Isognomon perna live at depths of 0-20m in tropical climates; byssally attach to rocks, reef flats, or the underside of boulders. Commonly found under rocks in shallow water and arranged one on top of the other.