means A marine bivalve mollusk with a distinctive fan-shaped, ribbed shell, prized as seafood — or, by extension, the wavy, curved edging shaped like that shell.

from From Old French 'escalope,' meaning a shell or shell-like covering, which is probably of Germanic origin, related to words for 'shell' or 'husk' (think of the same family that gives us 'scale' and 'shale'). The shape was so iconic that 'scallop' came to mean any rounded, wavy edge — and the verb 'to scallop' followed, for cutting cloth or pastry into those little curves.