That detail alone tells you what you are looking at. A fulacht fia is a prehistoric cooking site, typically Bronze Age, where stones were heated in a fire and then dropped into a water-filled trough to bring it to the boil. The spent, heat-shattered stones were raked out and piled up over time into the horseshoe-shaped mounds that survive across the Irish landscape. This one, grassed over and sitting quietly on rough grazing beside a small southward-flowing stream, measures roughly 11 metres north to south and just under 9 metres east to west, rising to a modest 0.6 metres at its highest point. Its open end faces east, abutting the stream that would once have supplied the water for the whole operation.

What makes Coolnatullagh worth pausing over is not just the single mound but the cluster. Two further fulachtaí fia lie approximately 15 metres and 50 metres to the south, and all three sit within a multiperiod field system that suggests the landscape here was organised and worked across several different eras. The setting reinforces that impression: a short valley hemmed in on the west, north, and east by low limestone bluffs covered in hazel scrub, with the stream rising just to the north of the mound. According to research by Jones, Carey, and Hennigar published in 2011, the three cooking sites form a coherent group within this broader archaeological complex. Whether they were used simultaneously, or represent activity returning to the same convenient water source across generations, is not something the ground surface alone can settle.