The one at Ballygarriff in County Mayo belongs to a category of site so common, and yet so poorly understood, that archaeologists still argue about what these places were actually for. The typical burnt mound consists of a crescent or horseshoe-shaped accumulation of fire-cracked stones and dark, charred soil, almost always found close to a water source. They date broadly to the Bronze Age, roughly 2000 to 500 BC, and are known in Irish as fulacht fiadh, a term sometimes translated as cooking pit of the wild, though that interpretation is contested.

The leading theory holds that burnt mounds were outdoor cooking sites, where stones were heated in a fire and then dropped into a water-filled trough to bring it to the boil. Experiments have shown this method works efficiently, and replica troughs have successfully cooked joints of meat. Other researchers have proposed uses ranging from textile preparation to bathing and brewing, and it is entirely possible that different sites served different purposes, or several at once. What remains consistent is the method: heat the stone, transfer it to water, discard it when it fractures. Over repeated use, the pile of spent, shattered stone grows into the low mound that survives today. The example at Ballygarriff sits within a Mayo landscape that contains numerous such monuments, a county whose boggy, water-retentive terrain preserved both the mounds and the organic materials sometimes found alongside them.