It is, in fact, a fulacht fia, one of the most common yet persistently mysterious monument types in Irish archaeology. These are the remains of ancient cooking sites, typically Bronze Age in date, where large quantities of water were heated by dropping fire-cracked stones into a trough. The broken, heat-shattered stones were discarded in a horseshoe-shaped mound around the trough, and it is this accumulated debris, now softened by millennia of soil and grass, that gives the monuments their distinctive low profile.

What makes the Garranes site particularly interesting is that it does not stand alone. It is one of a cluster of six such monuments in the immediate area, a concentration that suggests repeated, perhaps seasonal, use of this valley over a considerable period. Fulachta fiadh are often found near water sources, which would have been essential for filling the cooking trough, and low-lying, reclaimed pasture land of this kind frequently preserves such features precisely because it has never been ploughed. The grouping at Garranes points to a locality that held some practical or communal significance in prehistory, even if the specific nature of that activity remains a matter of debate among archaeologists.