The queen scallop is a small scallop species with a nearly circular shell and vivid red roe, harvested from deeper offshore waters than the larger great scallop. Two closely related species are recognised under the names Pecten opercularis and Chlamys opercularis. Its delicate, sweet flesh is smaller and more tender than that of its larger cousin, and the bright coral-coloured roe is considered a delicacy rather than discarded. Queen scallops are gathered by dredging or diving in the north-eastern Atlantic around the British Isles and are sold fresh or frozen, often in the shell. Like all bivalves they are filter feeders, so harvesting waters must be classified and monitored for biotoxins and bacterial contamination before the catch reaches market.