Learn about the following species groups (including their most common members, as well as purchasing, storage and cooking information), or select a specific species from the species list on the right.
Univalves, creatures with just one shell, are part of the larger class of land and sea creatures known as gastropods - commonly called snails. Sea snails include abalones, conches, periwinkles, cowries, whelks, limpets and numerous other creatures whose unusual shells are popular with collectors and have been put to many purposes, including decorative, ceremonial, as jewellery and even currency. The spiky murex shell of the Atlantic was the source of the purple dye used for royal robes in ancient times, while, large whelk shells were filled with fish oil and a wick and used as lamps in northern Scotland.
Apart from Abalones, the most common commercial sea snails in Australia are:
Periwinkles (Littorinidae, Neritidae and Turbo species) vary in size and shape as the name refers to a number of different families (though they’re usually around 7cm high or smaller). ‘True’ periwinkles are squat, while nerites are more rounded and turban shells are conical. The shells are often rough or ridged with a circular opening, and always have an operculum, the protective flap covering the opening. They’re found right around the Australian coast.
Trochus (Trochus niloticus) is a type of periwinkle, found around Australia’s northern coast, with a rough, conical, pointed shell (resembling a witch’s hat). Traditionally they were harvested for their shells which have a pearly inner surface used to make buttons and ornaments.
Bailer Shells (Zidoninae subfamily) are large, smooth, cream-coloured, oval, spiral-coiled shells with orange-brown zigzag markings; their name comes from their use in some areas for bailing out boats. The most common, false bailer shell with its distinctive orange foot, is harvested off the south-east coast, while a very similar, but less commonly seen, black-footed species is found along the central to north coast of NSW. The larger melon shells, named for their shape, are also less commonly seen commercially. Bailer shells lack an operculum, the protective flap found over the opening of many univalves.
Tun Shells (Tonnidae family) are large (about 10cm diameter), almost spherical shells with grooves running around the outside and relatively thin walls. The name ‘tun’, an old word for a wine barrel of a specific size, refers to the shell’s barrel-like shape.
Other univalves occasionally seen in retail shops or harvested recreationally in various parts of Australia include: Hercules Club Whelk (Pyrazus ebeninus) is found in mangroves and estuaries in Queensland, New South Wales and Victoria. It has a long spiral shell (about 11cm long) and is sometimes called Sydney mud whelk. Conches (Strombidae family) are found off northern Australia, but rarely harvested commercially. They have large, smooth, oval, spiral-coiled shells similar to bailer shells, but without the distinctive zigzag markings and with an operculum, the protective flap across the opening, which bailer shells lack. Tulip Shells (Fasciolariidae family) are long, pink, spindle-shaped shells found on sandy bottoms in tropical to temperate waters.
Smaller sea snails, such as periwinkles, are usually sold live; look for brightly coloured, intact, lustrous shells, firm flesh that retracts when touched, and a pleasant fresh sea smell. Larger shells, such as bailer shells, are generally packed with ice after harvesting and so arrive at market already dead, therefore the meat won’t retract when touched.
Live molluscs should be consumed as soon as possible after purchase. Place in a container, cover with damp paper or cloth and keep in the warmest part of the refrigerator, usually the crisper (optimum 5°C), ensuring that the covering remains damp. Store bailer shells in an airtight container in the fridge for up to 3 days, or extract the meat and freeze for up to 3 months below -18ºC.
Preparing & Cooking
Large univalves, such as bailer shells, are generally prepared by trimming off the intestines and tough outer skin to expose the meaty body and foot, which can be pounded to soften it or thinly sliced and pan-fried, deep-fried, stir-fried, steamed or braised. With shells that have large openings, such as abalone and large limpets, the raw meat can be cut from the shell and trimmed then cooked. Spiral-coiled shells with smaller openings, such as bailer shells, need to be cracked so the meat can be extracted. Smaller univalves are usually boiled in the shell and then removed with a pin or special fork and dipped into condiments such as aïoli or malt vinegar. They can also be baked or used in soups and are sometimes eaten raw or pickled. Many spiral-coiled univalves have an operculum, a protective hard piece of shell attached to the foot that covers the entrance, this needs to be cut off and discarded before eating.
Univalves around the world
* The name whelk refers to different univalves in different parts of the world, though the Buccinidae family are known as ‘true’ whelks. In Australia and New Zealand, members of the Ranellidae family are called predatory whelks. In the UK, certain members of the Muricidae and Nassariidae families are called dog whelk, while in Scotland periwinkles are called whelks. In the West Indies, whelks (or wilks) are a species of trochus shell (Cittarium pica) also called magpie or West Indian top shell.
* Cowrie, or cowry, members of the Cypraeidae family, have oval, porcelain-like shells, which have been used as currency (the word ‘porcelain’ derives from the Latin name for these shells, porcellana). Some members of the closely-related Ovulidae and Triviidae families are sometimes also called cowries.
* Chilean Abalone (Concholepas concholepas) also called loco, pata de burro and chanque, is native to the coasts of Chile and Peru; despite looking like an abalone it’s a member of the Muricidae family (murex or rock snails).
* Limpet generally refers to univalves with a simple conical shell that doesn’t appear spirally coiled, including ‘true’ limpets (Patellogastropoda group).