Small to medium in size, 25-75mm. Largest oyster still has mangrove root stuck to it. Smallest oyster has half of its shell missing. Some purpley colors on them, irridescence, had algae stuck to them. Were growing on a red mangrove root in an intertidal zone.
Found washed up on the beach.
15-cm long shell of a rather large freshwater oyster, that is apparently the primary food of a puffer fish living in the Niger River system. Unfortunately, this shell (& all others that I could find) was empty. Whether this species produces freshwater pearls could not be determined with the limited sample of empty shells available.
Los Angeles County, California, US
Large oyster beds in the intertidal zone.
Orange County, California, US
San Diego County, California, US