The one at Creggagh in County Mayo is a quiet example of a site type that appears almost everywhere in Ireland, often noticed only as a low, horseshoe-shaped mound of fire-cracked stone in a damp or marshy corner of a field. The name, loosely translating from Irish as something like "cooking place of the deer," reflects one long-held theory about their purpose, though what exactly went on at these sites has been debated for decades. Cooking, bathing, textile processing, and brewing have all been proposed, and the honest answer is probably that different sites served different needs at different times.

The typical fulacht fia consists of a trough, usually timber-lined or stone-lined and dug into the ground near a water source, alongside a hearth and the characteristic mound of shattered stones that accumulated as heated rocks were repeatedly plunged into water to raise its temperature. The stones crack and fragment with repeated heating and cooling, becoming useless for further heating, and so the mound grows over time. Most examples in Ireland date to the Bronze Age, roughly 1500 to 500 BC, though some have produced earlier or later dates. Mayo has a particularly dense distribution of these monuments, owing in part to the county's abundance of boggy, low-lying ground, which preserves both the stone spreads and the organic remains that allow radiocarbon dating. The Creggagh example sits within this broader pattern, one node in a network of prehistoric activity that stretched across the county over many centuries.