Roughly semicircular in shape and measuring about fifteen metres along its longer axis, it is composed not of earth or stone but of burnt material, the compacted debris of repeated heating and cooling. To a casual eye it looks like little more than an uneven rise in a field. To an archaeologist, it is immediately recognisable as a fulacht fia.

A fulacht fia is a type of prehistoric cooking site found in enormous numbers across Ireland, with County Cork alone containing several hundred recorded examples. The basic principle is straightforward: stones are heated in a fire, then dropped into a water-filled trough to bring it to a boil, after which meat could be cooked. The stones crack and shatter with each cycle of heating and quenching, and it is this accumulation of broken, fire-reddened stone that forms the characteristic horseshoe or crescent-shaped mound that survives at sites like this one. Most fulachtaí fia date to the Bronze Age, roughly 1500 to 500 BC, though some are earlier or later. Their consistent association with running water or streams is part of what makes this example at Ballinaboy so typical in its placement, set as it is on the southern bank of a stream, exactly where one would expect to find such a site. Whether the trough was timber-lined, stone-built, or simply a pit is something that only excavation could confirm here.