A fulacht fia is essentially an ancient cooking site, typically consisting of a horseshoe-shaped mound of fire-cracked stone and charcoal built up beside a water source. The standard interpretation is that stones were heated in a fire and then dropped into a water-filled trough to bring it to the boil, a method used for cooking meat, and possibly for other purposes including textile processing or even bathing. The example at Killeens in County Kerry is one such site, quietly occupying its place in the landscape as a low earthen mound that most passersby would take for a natural feature.

Fulachtaí fia date predominantly to the Bronze Age, roughly 1500 to 500 BC, though some examples have been recorded from later periods. The name itself is an Old Irish phrase sometimes translated as "cooking place of the wild" or associated in medieval texts with the roving hunter-warrior bands known as the Fianna. Kerry has a particularly dense concentration of these sites, which is partly a reflection of the county's wet, boggy terrain. Waterlogged ground both preserved the organic materials within the mounds and provided the ready water supply that the cooking process required. The cracked and shattered stone that defines these sites is the direct physical result of repeated thermal shock, as rocks were heated and plunged into cold water cycle after cycle over what may have been centuries of use.