To a passing eye it might register as nothing at all, a slight rise in a wet field. But the material underneath the turf tells a different story: burnt stone and ash, the characteristic debris of a fulacht fia, the prehistoric cooking or industrial sites found in their thousands across Ireland, typically beside running water. The mound here measures roughly eight metres east to west and just over five and a half metres north to south, and where the rivulet runs closest, along its southern edge, the stone fill is exposed.

A fulacht fia, in the simplest terms, is a mound of fire-cracked stone accumulated beside a water source. The standard interpretation is that stones were heated in a fire and dropped into a water-filled trough to bring it to the boil, though debate continues about whether the primary purpose was cooking, bathing, brewing, or some combination of these. The site at Clooncoose was formally identified following a 1994 survey by Tom Coffey, which recorded four fulachtaí fia in the area, and the site was listed in the Record of Monuments and Places in 1996. Notably, a second fulacht fia lies approximately eleven metres to the south-west, making this a small cluster of related activity in what would have been, in prehistory as now, a reliably wet and low-lying landscape enclosed by higher ground on all sides.