It is, in fact, a fulacht fia, one of the most common prehistoric monument types in Ireland, and one of the more intriguing in terms of what it represents. A fulacht fia is essentially a Bronze Age cooking site, typically consisting of a horseshoe-shaped mound of burnt and shattered stone surrounding a trough, where water was heated by dropping fire-cracked rocks into it. The stones, fractured by repeated heating and cooling, were discarded into the mound over time, building it up gradually. The one at Killuney is subcircular in plan, measuring roughly fifteen metres north to south and just under fourteen metres east to west, rising to about a metre in height, with a depression of nearly four metres visible on its north-eastern side where the trough would once have been.

What makes this particular example slightly more interesting than its understated exterior might suggest is its early modern history. According to local information, the mound was excavated in 1931 or 1932 by a Dr T. B. Costello of Tuam, an intervention that predates many of the methodological standards now expected of archaeological fieldwork. What Costello found, and what records he may have left, is not clear, though the mound is described as well-preserved, suggesting his digging did not drastically alter its form. The site sits in low-lying marshy ground, the kind of damp, stream-adjacent terrain that fulachtaí fia consistently favour, presumably because proximity to water was essential to their function. A second fulacht fia lies around two hundred metres to the west-northwest, making this a locality where Bronze Age activity appears to have been repeated or sustained over time.