The one at Clenagh in County Clare is a quiet example of this wider enigma. A fulacht fia typically survives as a low, horseshoe-shaped or kidney-shaped mound of burnt and cracked stone, usually found close to a water source. The stones were heated in a fire and dropped into a water-filled trough to bring it to the boil, a method that leaves behind a distinctive spread of fire-shattered rock that can endure for millennia.

Most fulachtaí fia date to the Bronze Age, roughly 1500 to 500 BC, though some have produced dates ranging outside that window. What they were actually used for has generated considerable debate among archaeologists. Cooking meat is the traditional explanation, and experimental archaeology has shown the method works efficiently. More recent proposals include brewing, hide preparation, textile processing, and even bathing. No single explanation has settled the argument, which is part of what makes each example worth pausing over. The Clenagh site sits within a county that has produced a notable number of these monuments, Clare's landscape being well suited to their preservation in low-lying, occasionally waterlogged ground.