Abalone ( or ; via Spanish , from Rumsen aulón) is a common name for any of a group of small to very large marine gastropod molluscs in the family Haliotidae. Other common names are ear shells, sea ears, and, rarely, muttonfish or muttonshells in parts of Australia, ormer in the UK, perlemoen in South Africa, and paua in New Zealand. Abalones are marine snails. Their taxonomy puts them in the family Haliotidae, which contains only one genus, Haliotis, which once contained six subgenera. These subgenera have become alternate representations of Haliotis. The number of species recognized worldwide ranges between 30 and 130 with over 230 species-level taxa described. The most comprehensive treatment of the family considers 56 species valid, with 18 additional subspecies. The shells of abalones have a low, open spiral structure, and are characterized by several open respiratory pores in a row near the shell's outer edge. The thick inner layer of the shell is composed of nacre (mother-of-pearl), which in many species is highly iridescent, giving rise to a range of strong, changeable colors which make the shells attractive to humans as decorative objects, jewelry, and as a source of colorful mother-of-pearl. The flesh of abalones is widely considered to be a desirable food, and is consumed raw or cooked by a variety of cultures. Description Most abalone vary in size from (Haliotis pulcherrima) to . The largest species, Haliotis rufescens, reaches . The shell of abalones is convex, rounded to oval in shape, and may be highly arched or very flattened. The shell of the majority of species has a small, flat spire and two to three whorls. The last whorl, known as the body whorl, is auriform, meaning that the shell resembles an ear, giving rise to the common name "ear shell". Haliotis asinina has a somewhat different shape, as it is more elongated and distended. The shell of Haliotis cracherodii cracherodii is also unusual as it has an ovate form, is imperforate, shows an exserted spire, and has prickly ribs. A mantle cleft in the shell impresses a groove in the shell, in which are the row of holes characteristic of the genus. These holes are respiratory apertures for venting water from the gills and for releasing sperm and eggs into the water column. They make up what is known as the selenizone, which forms as the shell grows. This series of eight