Pseudochama exogyra (Conrad, 1837)
Common name(s): Reversed chama, Jewel box
|Pseudochama exogyra on rock among coralline algae at Laguna Beach, CA|
|(Photo by: Dave Cowles May 1998)|
How to Distinguish from Similar Species:Chama arcana is attached by its left valve & has a waxy-translucent exterior. Its beak coils to the right (clockwise) as viewed from above.
Geographical Range: Oregon to southern Baja California. Not likely to be found north of Oregon
Depth Range: Middle intertidal
Habitat: On rocky reefs along the outer coast
Biology/Natural History: Often in large clusters on rocks along the outer coast. Often with Chama arcana and the tube snail Serpulorbis in California. Valves are thick and dense; apparently lack calcite. Related to the extinct (Mesozoic) group of rudists. The shell rotates (clockwise?) while it grows, leading to the spiral lines.
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Morris et al., 1980
A cluster of Pseudochama exogyra on the rocks among algae. Note the barnacles on some of the valves. Photo by Dave Cowles, Laguna Beach, CA 1999