A cockle is a bivalve form of mollusk, commonly identified by its heart-shaped shell. The cockle is sometimes referred to as the "heart clam." The shell of the cockle is noticeably rounded and strong, usually with many symmetrical radial ribs. The 200 varieties of cockles range in size from a quarter of an inch to six inches, and can be red, brown or yellow.
In North America, cockles can be found on both the east and west coasts. Cockle hunters on the west coast will find the Giant Pacific cockle, with shells up to six inches, and the egg cockle, which is the only type to have a smooth shell. On the East coast can be found the prickly, yellow, Atlantic strawberry and great heart cockle varieties. In northern Europe, the predominant variety is the common cockle, which is used as a food source in England, Wales and Ireland.
Cockles are considered a delicacy in the coastal areas of Great Britain. They are generally served boiled with vinegar and pepper, but can also be purchased pickled in jars. In Wales, cockles fried with bacon and served with laverbread (a seaweed paste) is a traditional breakfast offering. Cockles are mentioned in the Irish folk ballad "Molly Malone" because of the fact that street vendors and hawkers traditionally sold fried cockles on the street.
There is some danger in eating and gathering cockles. They should always be served well cooked, because eating raw or undercooked cockles can lead to hepatitis. In addition, because cockles are found in the sand around the tide line, there is some risk to gathering them. In 2004, 18 immigrant workers died while collecting cockles in Morecambe Bay, England. The workers had mistaken the time of the incoming tide and were quickly washed out to sea when it came in quickly and with little warning.