noun
cockle
KAH-kul/ˈkɑːkl/
A small edible sea animal with a ridged, two-part shell.
The cockle rests on wet sand with its ridged shell slightly open.

Etymology
Greek konkhylion meant “little shellfish,” a diminutive of a word for a mussel or conch. English preserves that shellfish connection in the name of this particular edible mollusk.
In context
for every cockle you get you've got to carry shells weighing well over 10 times the weight of the edible fish inside
More examples
- We gather cockles from the wet sand at low tide.
- Each cockle has a shell made of two hinged halves.
- She serves the cockles with garlic butter and bread.
Forms
cockle · cockles
cockleshell noun — The rounded, ridged shell of a cockle.