This large red sea urchin (Strongylocentrotus franciscanus) shell or test was found on a dive near Campbell River, BC. The test is made up of calcium carbonate to give it strength and can be around 6 inches (15 cm) in diameter. The many bumps on the test are where the spines were once attached. A cup-like base to each spine would rest over these bumps. A living red sea urchin can use muscles and tissue attached to the spines to direct them towards a threat. The red sea urchin is a herbivore, and grazes on nearby algae. Their long sharp spines are red to purple-black in colouration. The red sea urchin can grow to 12 inches (30 cm) across, with a range that includes Japan, as well as northern Alaska to northern Mexico.
