It is horseshoe-shaped, a form that immediately signals its purpose to anyone familiar with prehistoric Irish archaeology. This is a fulacht fia, a type of ancient cooking site found in enormous numbers across Ireland, typically dating from the Bronze Age. The characteristic shape comes from the gradual accumulation of fire-cracked stone: rocks were heated in a fire, then dropped into a water-filled trough to bring it to a boil, and the shattered, spent stones were simply piled to either side, building up over repeated use into the curved mound that survives today.

The Ballyshoneen example measures roughly 19.5 metres in length and 13 metres in width, with a height of around half a metre, placing it comfortably within the range typical of these sites. Its opening, about 2.5 metres wide, faces south-east, and the whole structure sits on the southern bank of a small stream, which would have supplied the water essential to the cooking process. The marshy ground around it is itself characteristic; fulachtaí fia are almost invariably found in low-lying, wet areas, close to a reliable water source, and the waterlogged conditions that make such spots inconvenient for farming are often precisely what has preserved these sites through the centuries.