It measures roughly 3.4 metres by 2.4 metres and rises only 0.6 metres at its highest point, with a depression where the trough once sat, opening towards the upper slopes. Easy to miss, and easier still to mistake for a natural feature of the hillside, it is in fact the remains of a fulacht fia, one of the most common yet least-understood monument types in the Irish landscape.

A fulacht fia is a Bronze Age cooking place, typically found near water and identified by its characteristic spread of fire-cracked stone. The method was straightforward: stones were heated in a fire, then dropped into a water-filled trough, bringing it rapidly to a boil and keeping it there long enough to cook meat. Over repeated use, the shattered, spent stones were discarded into a crescentic or horseshoe-shaped mound around the trough, which is precisely the form preserved here at Cornamucklagh. The positioning on a mountain shelf beside a stream is entirely typical; reliable running water was essential to the whole process. What is slightly less common is the orientation of the trough depression facing upslope rather than down, a small detail that hints at how the site was arranged in relation to its immediate terrain.