Beneath the surface, however, lies a spread of burnt and shattered stone roughly nine metres across, the calling card of a fulacht fia. These are among the most common prehistoric monuments in Ireland, yet they remain genuinely puzzling. The term refers to a type of cooking or industrial site, typically Bronze Age in date, where stones were heated in fire and then dropped into a water-filled trough to bring the liquid to a boil. The repeated heating and cooling caused the stones to crack and splinter, and over generations the discarded fragments accumulated into the characteristic horseshoe-shaped or oval mounds that survive across the Irish landscape today.

The Killabraher example measures approximately nine metres east to west and 8.8 metres north to south, making it a reasonably substantial example of the type. It survives as a grass-covered spread of burnt material in agricultural land, the kind of monument that endures because it was never worth the effort of clearing. Fulachtaí fia were long assumed to be purely for cooking, perhaps boiling large joints of meat during seasonal gatherings, though more recent research has raised the possibility that some were used for brewing, hide processing, or even bathing. Without excavation it is impossible to say which function, if any single one, applied here, and the site at Killabraher carries no visible clues beyond its dimensions and the scorched stone that lies beneath the turf.