A fulacht fia is a prehistoric cooking site, typically consisting of a horseshoe-shaped mound of fire-shattered stones surrounding a timber-lined trough into which water was heated by dropping in stones from an open fire. Thousands survive across Ireland, usually close to streams or boggy ground, and the example at Caherbarnagh fits the pattern precisely, sitting alongside a field boundary and a stream, with a wet marshy area immediately to its east.

The mound was formally recorded in 1995 and measured roughly 13.9 metres in diameter and about a metre in height, with a shallow central depression of around 0.3 metres and an opening facing south-west. These dimensions are fairly typical for the monument type, which tends to accumulate its distinctive profile over repeated use as spent, heat-fractured stones are discarded to the sides of the trough after each firing. The charcoal-enriched soil identified at the site is another reliable indicator of sustained, repeated burning, and fragments of heat-shattered stone were still visible extending beyond the wire fence erected to protect the mound.

Since the recording, the surrounding field has been planted with coniferous trees, which has changed the character of the immediate landscape considerably. The fulacht fia itself is fenced off and densely overgrown with briars, making close inspection difficult, though the mound shape and the scatter of fractured stone remain identifiable beneath the vegetation. The marshy ground to the east is a useful locating feature, as prehistoric communities consistently chose spots where water was close to hand and reliably available.