Clams are edible, bivalve shellfish found in sandy coastal waters throughout the world. They vary from tiny and dull in colour to as much as 15 cm (6 inches) across. They have an almost circular shell and are generally available pickled in brine or vinegar. However, they can be found fresh in some parts of the world in which case they can be eaten either raw or steamed for around five minutes and checked in the same way that you would mussels. Smaller clams include cherrystones, carpet shells, little necks, steamers or soft-shelled clams and Venus. Larger ones, which are often used in chowders, include hard shell clams and ocean quahogs. In practice the same words are often used for both clams and cockles. Cockles are less sweet than the more favoured clams which is why they are more often used in sauces, soups or in ready-made dishes. If clams are being used, the variety is frequently named in may parts of the world.