This image is a close-up of a limpet shell found on Okinawa. A limpet is a mollusk; in this case a “univalve” instead of a “bivalve” clam. In life, a limpet uses the strong muscles in its foot to adhere to a hard surface. It moves slowly and generally consumes algae scraped off that area of attachment. This limpet species is about one inch across, and has a zig-zag zebra pattern, brown/black against white. This limpet is roughly conical with multiple distinct ridges running from the crown to edge of the shell.