Abalone, or perlemoen, are molluscs, as are clams, scallops, sea slugs, octopuses and squid. Molluscs have a soft body surrounded by a mantle, a head and a large muscular foot. The spiral structure, so common in snail shells, is flattened in the abalone shell. It is shaped like an ear, with a row of breathing pores down one side. Shells are prized because of their inner, iridescent layer, called mother of pearl. Abalone are a delicacy in the far east and high prices are paid for them, leading to successful abalone farming, as well as illegal harvesting.