The common cockle is a bivalve mollusc found buried in mud and sand in estuaries and on beaches. Cockles have distinctive rounded shells that are slightly heart shaped. It is a bivalve (two identical shells) belonging to the family Cardidae meaning heart-shaped. An organ called a siphon allows the animal to feed and breathe whilst buried in the sand. They can jump by bending and straightening the foot - the end bit- which is often coloured red and called the red nosea. The shell size is up to 5cm long, although average sizes tend to be around 3-4cm. Maturity occurs at a shell length of around 2cm. Cockles spawn from March to August, although exact times will vary from region to region.