The 'cockles of your heart' may owe their name to a heart-shaped shellfish
Seen end-on, a cockle's ribbed shell looks like a heart, and the family's type genus, Cardium, takes its name from the Latin for heart. That may explain why good news 'warms the cockles of your heart', though rival theories point to Latin words for the heart's ventricles or a little heart.
True cockles belong to the family Cardiidae, with more than 205 living species and many more known only as fossils. They live buried in sheltered sandy beaches worldwide, burrowing with a muscular foot and filtering plankton from the water. By bending and straightening that foot, a cockle can even jump. Its shell closes completely, and although the ribs resemble a scallop's, cockles lack the ear-like flaps near the hinge and stay in the sediment rather than swimming off when threatened.
Fishmongers stretch the name to other small clams. The dog cockle of northern European shores sits in a separate family and is edible but so tough when cooked that people rarely bother. The blood cockle, farmed widely from southern Korea to Malaysia, is actually an ark clam. The common cockle, meanwhile, ranges from the Barents Sea down to Senegal.
Cockles are eaten across the world. In Southeast Asian hawker centres they go into laksa and char kway teow, Cambodian street vendors serve them with a dip of crushed pepper, salt and lime, and in Japan the egg cockle becomes torigai sushi. British seaside stalls sell them boiled with malt vinegar and white pepper, and cockles fried with bacon and served with laverbread make a traditional Welsh breakfast. They also appear in the refrain of the song about Molly Malone.
Gathering them carries real risk. Pickers rake cockles from the sand at low tide, and in the Morecambe Bay disaster 23 of them drowned when high tide caught them. Rules limit casual harvesting: as of 2011, anyone in England and Wales could take 8 pounds for personal use, but more than that counted as commercial fishing and needed a permit.
Source: Cockle (bivalve)
