Pacific Thorny Oyster
Spondylus princeps (Pacific Thorny Oyster) is a genus of bivalve molluscs, the only genus in the family Spondylidae. They are known in English as spiny oysters (though they are not, in fact, true oysters). [wiki]
The genus Spondylus appeared in the Mesozoic era, and is known in the fossil records from the Triassic Cassian beds in Italy (235 to 232 million years ago) onward. About 40 extinct species are known.
Where they are found
Pacific Spiny Oysters are found on vertical surfaces at depths between 35 and 300 feet. They range from Scammon's Lagoon, Baja California south to Ecuador and are found in the Sea of Cortez from Bahia Williard, Baja California south to Cabo San Lucas, Baja California Sur.