What exists here, according to local knowledge, is a spread of burnt material beneath the surface, the buried remnant of a fulacht fia, with nothing above ground to mark the spot.

A fulacht fia is a type of prehistoric cooking site found in enormous numbers across Ireland, typically dating from the Bronze Age. The usual form consists of a horseshoe-shaped mound of fire-cracked stone beside a trough, sometimes timber-lined, into which water was poured and heated by dropping stones from a fire directly into it. Thousands of these sites survive as low, often waterlogged mounds in fields and boggy ground, making them one of the most common monument types in the Irish landscape. The Knocknagallagh example, however, belongs to a less visible category. The burnt stone scatter that identifies it as a fulacht fia survives only below the surface, with no mound or depression remaining to catch the eye of a passing walker. What is known of its location comes from local information rather than any surviving physical feature that can be observed at ground level.