Also known as Fan Shell, Great Silk Muscle, Oyster, Pacific Pen Shell, Pearl Oyster, Pen Shell, Sea Ham, Thorny Wing.
Found on mixed soft bottom substrates partially buried in a vertical position amongst eelgrass flats and sandy patches of coral and rocky reefs.
They feed on plankton.
This is a triangular shell with rows of small triangular spines (look like skin tags)
Length - 31cm
Depth - 0-40m
Most Bivalves are permanently anchored in fissures or depressions in the rock surface of the reef, some may become covered in algae and other marine life.
Other Bivalves swim free, either by a well developed foot or propelled along by a jet of water from their mantle cavity. Ref: https://www.sealifebase.ca/summary/Pinna-muricata.html