Isognomon californicus, the black purse shell or nahawele in Hawaiian, is a species of bivalve in the family Isognomonidae.

It was first formally named in 1837 by Timothy Abbott Conrad as Perna californica.

This species can be found in brackish environments in crevices near or around the high tide line.

[1][2] The Black Purse Shell often looks flat, thin, and irregular in appearance with a flaky exterior and pearly interior.

Black purse shells happen to be a very small species of mollusks only growing to be around one to one and a half inches in length.