This is the most unusual looking sponge I’ve noticed so far covering a spiny pink scallop (Chlamys hastata). The spiny pink scallop is also known as a swimming scallop. If this animal is disturbed by certain sea stars it may start closing and opening its shells which offer a form of propulsion, allowing the scallop to lift up into the water column and fall downwards a short distance away, hopefully avoiding predation. This scallop has sharp spines on the radiating shell ridges. Often these spines and ridges are hidden beneath sponges living on the shells. The spiny pink scallop can grow to 3.7 inches (9.3 cm) across, and has a range from northern Alaska to southern California.