Casmaria erinaceusCasmaria erinaceus, common name : the common bonnet, is a species of large sea snail, a marine gastropod mollusk in the family Cassidae, the helmet snails and bonnet snails.DescriptionThe size of an adult shell varies between 20 mm and 79 mm.DistributionThis species occurs in the Red Sea, in the Indian Ocean along Aldabra, Madagascar, the Mascarene Basin and Mauritius; in the Pacific Ocean along Melanesia, Micronesia and the Philippines.