In archaeology a conchal is a man-made accumulation of marine invertebrate shells usually found on beaches. They constitute often an unequivocal sign of human occupation but are however prone to be eroded, buried by sand dunes or washed away by transgressions or tsunami waves. The term comes from the Spanish and derives from the Spanish word for mollusc shell, concha. Among coastal nomadic peoples, conchales may be one of the few signs that shows specific areas of human occupation.