The site covers roughly fifteen metres in each direction, a modest but legible footprint of burnt stone and organic material left behind by people who almost certainly used the nearby water as part of their process. The typical method involved heating stones in a fire and dropping them into a water-filled trough to bring it to a boil, a technique that leaves the stones cracked and blackened and eventually builds up the characteristic mound that survives today.

What sharpens the picture at Carrigleagh is a find made approximately eighty metres to the south-south-west, in the same field: a barbed and tanged chert arrowhead. Barbed and tanged arrowheads, shaped from flint or chert with deliberate notches to seat a wooden shaft, are generally associated with the late Neolithic and early Bronze Age, a period running roughly from 2500 to 1500 BC. The arrowhead does not prove a direct connection to the fulacht fia, but its proximity suggests repeated human activity across this particular stretch of ground over a considerable span of time. The site sits in tillage land, which means the upper layers have been subject to regular ploughing, the kind of gradual disturbance that disperses surface finds and can blur the original boundaries of a feature like this.