What they found was a fulacht fia, the term used for a type of Bronze Age cooking or industrial site consisting of a burnt mound, a trough or pit for holding water, and the remains of hearths used to heat stones. The stones were typically fired and then dropped into the water-filled trough to bring it to a boil, after which they fractured and were discarded in a crescent-shaped mound nearby. The sheer number of features at Coolbeg sets it apart: two burnt mounds, five troughs, and at least four hearths were uncovered across a single excavation area.

One of the five troughs was wood-lined, a detail that speaks to some care in construction, since timber would have helped retain water and prevent the sides from collapsing under repeated use. Alongside the structural remains, the excavation produced around 180 lithics, the collective term for worked stone tools and flakes, as well as 19 sherds of prehistoric pottery. Radiocarbon dating placed the site's activity across a broad span, with dates ranging from 2290 to 2030 BC, 2210 to 2020 BC, and 1980 to 1760 BC. That spread of dates suggests the site was not a single episode of use but rather a place people returned to across generations, well into the middle Bronze Age. The excavation was carried out under licence in advance of development, the kind of rescue archaeology that frequently recovers material which would otherwise be lost without record.