Large oyster beds in the intertidal zone.
Orange County, California, US
San Diego County, California, US
On a mangrove trunk.
Being produced in the mudflats of the Ria de Aveiro lagoon. The Portuguese oyster, Crassostrea angulata, was replaced by its Pacific congener during the last half of the 20th century because of its vulnerability to viruses and parasites and reduced growth. In Portugal, pure populations (i.e. non-hybrid) of C. angulata can only be found in the Sado estuary.
Shell only...probably dropped by birds