They appear as low, horseshoe-shaped mounds, typically found close to water, and for a long time nobody was entirely sure what they were for. The leading theory holds that they were cooking sites, perhaps used over many centuries during the Bronze Age: a trough dug into the ground would be filled with water, stones heated in a nearby fire would be dropped in to bring it to the boil, and meat could then be slow-cooked. The burnt and shattered stones were piled to the side after each use, gradually forming the distinctive mound that survives today. The example at Cloongee in County Mayo is one of countless such sites recorded across the country, though it sits in a part of the west of Ireland where the boggy, low-lying ground has done much to preserve ancient features that elsewhere have long since vanished beneath the plough.

Mayo has a particularly dense scatter of prehistoric monuments, partly because the blanket bogs that cover so much of the county act as a slow, cold archive, sealing organic material and earthworks beneath layers of peat. The fulacht fia at Cloongee belongs to this broader pattern of Bronze Age activity across the landscape, a period running roughly from 2500 to 500 BC during which communities left their mark in the form of cooking mounds, burial cairns, and field systems. Many of Mayo's fulachtaí fia remain as slight rises in rough pasture or bog, easy to walk past without recognising them for what they are.