It is roughly circular, about twelve metres across and only half a metre high, and it has been partially destroyed. What remains is the signature residue of a fulacht fia, a type of prehistoric cooking site found in their thousands across Ireland, almost always close to water and almost always in low-lying, wet terrain.

A fulacht fia typically consisted of a trough, dug into the ground and sometimes lined with wood or stone, which was filled with water. Stones were heated in a nearby fire and then dropped into the trough to bring the water to a boil, a method used for cooking, and possibly for other purposes including bathing or textile production. The discarded burnt and shattered stones accumulated over repeated use into a horseshoe-shaped or rounded mound, which is exactly what survives here at Kilcullen. These sites are generally dated to the Bronze Age, though some were in use later, and their clustering near rivers and boggy ground is so consistent that the waterlogged soil has often helped preserve them where drier ground would have left nothing at all. The site at Kilcullen fits this pattern precisely, sitting in the marshy margins beside the Rylane River in mid Cork.