What they uncovered instead, at roughly forty centimetres down, were three distinct spreads of heat-shattered stone, the kind of material that accumulates over centuries of repeated burning and quenching, and which archaeologists associate with fulachta fiadh, the ancient cooking or industrial sites found throughout Ireland.

Fulachta fiadh, sometimes translated loosely as "cooking places of the wild," are among the most commonly recorded prehistoric monument types in Ireland. They typically appear near water, where stones were heated in fire and then dropped into a trough or pit to bring water to the boil. The cracked, fire-damaged stones were thrown aside after use, gradually building up into the low, horseshoe-shaped mounds that occasionally survive as slight humps in pasture fields today. At Kilcoole, the trench, which measured 1.3 metres deep and 0.75 metres wide and ran parallel to a small stream marking the townland boundary with Bullford, cut through this buried material without any surface trace having suggested it was there. The most substantial spread extended for approximately six metres and was visible on both faces of the trench; the other two spreads, lying close by, were largely obscured once the trench was partially backfilled to accommodate the ducting pipes. A mill race to the west of the site hints at the longer history of water use in this particular corridor of land.

Because the trench was backfilled before the full extent of the deposits could be assessed, the site remains only partially understood. The find came to light through monitoring work carried out under licence during development, rather than through any targeted investigation, which is how a considerable number of such sites come to be recorded in Ireland each year, quietly, beneath ground that has long since been levelled and built over.