They appear as low, horseshoe-shaped mounds, typically beside a water source, and are thought to date mainly from the Bronze Age. The leading theory holds that they were cooking sites: stones were heated in a fire and dropped into a water-filled trough until the water boiled, allowing meat to be cooked efficiently. Experiments have shown the method works remarkably well. Other theories propose they served as saunas, dyeing vats, or brewing facilities, and the debate has never been fully settled. The example at Ballykilty in County Clare is one of many such sites quietly occupying the Clare landscape, largely unannounced and easy to walk past without a second glance.

Clare has a dense concentration of prehistoric monuments, and fulachtaí fia are well represented among them. The townland name Ballykilty, like many in the county, preserves layers of older Gaelic nomenclature that predate the monuments themselves by centuries of linguistic change. Bronze Age communities in Ireland, broadly active between around 2000 and 500 BC, left these cooking mounds as some of their most durable traces, the burnt and shattered stone resisting the kind of decay that claims timber and organic material. The mounds survive precisely because the fire-cracked stone they are built from is of little agricultural or building use, making them oddly resilient against the centuries of land clearance that removed more conspicuous structures.