This is a fulacht fia, a type of prehistoric cooking site found in large numbers across Ireland, typically dated to the Bronze Age. The usual interpretation is that stones were heated in a fire, dropped into a water-filled trough to bring it to the boil, and used to cook meat, though some archaeologists have suggested the structures may also have served for bathing, brewing, or textile working. What makes the form so recognisable is precisely what you can see here: a horseshoe or kidney-shaped mound of fire-cracked, heat-shattered stone, built up over many uses, curving around a central trough where the water was held.

The Knockaunakill example measures 15.2 metres on its longest axis, running roughly northwest to southeast, and 10 metres across. It rises to around 0.6 metres at its northern end and a full metre at the south, modest in height but solid in presence. The trough area, the working hollow at the centre of the structure, is marked by a depression roughly 2 metres wide, opening out towards the edge of the small rivulet at the southwest, which would have supplied the water essential to the whole process. Two hawthorn bushes have taken root in the trough hollow, their presence a small reminder of how thoroughly vegetation reclaims these ancient workspaces once the fires go cold.