Encrusting coralline algae (Callilithophytum sp., Crusticorallina sp.) grows over rocks and hard surfaces like snail shells. There are many species of these algae in the Pacific Northwest and microscopic examination as well as DNA testing may be needed for identification. Calcium carbonate lining the cell walls of these red algae creates a hard surface. Encrusting coralline algae exists along coastlines around the world, with a West Coast range from northern Alaska to Chili.