The one at Teeronea in County Clare is a quiet example of a type that has puzzled researchers for generations. A fulacht fia typically survives as a horseshoe-shaped mound of burnt and shattered stone, usually found close to a stream or boggy ground. The working theory, broadly accepted today, is that these were outdoor cooking sites, in use from the Bronze Age onward. Water was channelled or collected into a trough, and stones heated in a nearby fire were dropped in to bring it to the boil. Repeated heating and rapid cooling fractures the stone, which is why the mounds contain so much shattered material. Some archaeologists have proposed alternative uses, including brewing, hide-working, or bathing, and the debate has never been fully settled.