It measures roughly fifteen metres north to south and thirteen metres east to west, and at its centre someone, at some point, has removed material, leaving a slight hollow in what was already an unassuming feature. A stream runs to the east. To the casual eye it might pass for a natural rise in the ground, the kind of thing sheep graze around without a second thought. It is, in fact, a fulacht fia, and it has been there for a very long time.

A fulacht fia is a type of prehistoric cooking site found in enormous numbers across Ireland, most dating to the Bronze Age. The basic principle involves heating stones in a fire, dropping them into a water-filled trough to bring the water to a boil, and using the resulting heat to cook meat. The burnt and shattered stones, discarded after each use, accumulate over time into the horseshoe-shaped or irregular mounds that survive in the landscape today. The dark, heat-fractured stone that makes up these mounds is distinctive, and at Caherbirrane the burnt material is still visible beneath the vegetation. The presence of the stream nearby is entirely typical; fulachtaí fia are almost always found close to a reliable water source, since the whole process depends on a ready supply. The removal of some material from the centre of this mound is a familiar complication at such sites, where the dark fertile soil has sometimes been dug out for agricultural use, or disturbed by later activity, leaving the record incomplete.