A young giant rock scallop (Crassadoma gigantea) was noticed filtering plankton from the surrounding ocean water. Once a bit older this rock scallop blends extremely well into its environment as surrounding life continues to attach and hide the shell valves. This small scallop can eventually grow to about 10 inches (25 cm) across, and live longer than 20 years. Giant rock scallops have been harvested for food in the past by the First Nations people of the Pacific Northwest. If an empty shell is found a purple stain can be seen where the hinge was located. The giant rock scallop has a range from northern Alaska to northern Mexico.