Noetia ponderosa explained

Noetia ponderosa, or the ponderous ark clam, is a marine clam in the family Noetiidae.^[1]

Description

The shape of the shell is rounded trigonal, almost as high as long,
with 27-31 squared radial ribs divided by fine incised lines,
and a distinctive brown or black periostracum. The exterior and interior of the shell is a white color. Size approximately 50–60 mm.

Right and left valve of the same specimen:

Distribution

Atlantic coast of North America, ranging from Virginia to Florida,
West Indies, Gulf of Mexico, and Caribbean Central America.^[2] ^[3]

Habitat

Noetia ponderosa typically resides in shallow water on the ocean floor.

Notes and References

Web site: WoRMS - World Register of Marine Species - Noetia ponderosa (Say, 1822). 2021-03-06. marinespecies.org.
Abbott, R.T. & Morris, P.A. A Field Guide to Shells: Atlantic and Gulf Coasts and the West Indies. New York: Houghton Mifflin, 1995. 11.
Book: Mikkelsen, Paula M.. Seashells of southern Florida : living marine mollusks of the Florida keys and adjacent regions, bivalves. 2008. Princeton University Press. Rüdiger Bieler. 978-0-691-11606-8. Princeton. 78071775.