Pododesmus cepio

The Jingle Shell or The Rock Oyster

Phylum Mollusca
Class Bivalvia
Order Pterioida
Family Anomiidae
Genus Pododesmus
Species cepio

Description: 4 to 6 cm across; shell is white; flesh is bright orange; outer valve is usually covered by algae, sponges, and bryozoans; the rounded, flat, valves are thin and conform to the surface to which the animal is attached; the lower valve is smaller and has a hole through which the byssal threads run through and attach to surfaces.

Habitat: Found growing in bays and harbors on rocks, docks, floats and pilings.

Natural History: While this animal filter feeds, its valves are slightly agape and the bright orange color can be seen. Its shell can grow to conform with the substrate to which it is mounted, often at obscure angles. A fossil species Pododesmus dunhamorum is the earliest known species of this genus. This fossil was found in the upper part of the Cresent Formation on the west side of Dabob Bay, Jefferson County, Washington on the Eastern Olympic Penninsula.