The whole deposit measured roughly ten and a half metres east to west and eight metres north to south, the characteristic footprint of a fulacht fia, a type of ancient cooking or heating site found in great numbers across Ireland. The working principle was straightforward enough: stones were heated in a fire and then dropped into a water-filled trough, bringing the water to a boil. Over repeated use, the shattered, heat-spent stones were raked out and piled to the side, eventually forming the low crescent-shaped mound that survives above ground at many of these sites.

At Killoran, excavation revealed not one but several intercutting troughs, suggesting the site was used over a sustained period or returned to on multiple occasions. The first trough, a roughly subcircular pit about 2.3 metres long, 1.8 metres wide, and nearly half a metre deep, was filled with grey clay, fire-cracked stones, and silty charcoal-rich deposits. Radiocarbon dating of that charcoal placed its use somewhere between 2585 and 2195 BC, placing it firmly in the Early Bronze Age. A second oval pit of similar dimensions cut into the northern edge of the first, indicating the site was extended or reworked rather than simply abandoned. What makes the Killoran site additionally notable is its setting within a cluster: a further burnt mound and fulacht fia lay just ten metres and sixty metres away respectively, suggesting this stretch of ground was a focus of repeated prehistoric activity rather than an isolated episode.