Cockles are small, round saltwater clams with heart-shaped shells that live buried in sand or mud along ocean shores. When you walk on a beach at low tide, you might spot their ribbed shells scattered among the seaweed and rocks. People have been gathering and eating cockles for thousands of years, steaming them open or cooking them in soups and stews.

The shells have distinctive ridges radiating out from the hinge, like the grooves on a scallop shell but rounder and plumper. In some coastal towns, people still rake through the sand at low tide to collect cockles for dinner, a practice called cockling.

You'll also hear cockles in the old phrase “warm the cockles of your heart,” which means something makes you feel happy and content deep down inside. When your grandmother says seeing you “warms the cockles of her heart,” she means your visit fills her with genuine joy and affection, the kind of warmth that reaches right to the center of who she is.