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. References

Pteriida
Molluscs of the Pacific Ocean