This is a fulacht fia, a type of site found widely across Ireland and typically interpreted as a Bronze Age cooking place, though some archaeologists have proposed alternative uses including textile processing or bathing. The method was straightforward: stones were heated in a fire and dropped into a water-filled trough until the water boiled. The cracked and shattered stones were then discarded to the side, accumulating over repeated use into the distinctive mound that survives today.

The mound at Lissacapia measures 13.3 metres in length, 6.2 metres in width, and stands just 0.35 metres high, its modest height reflecting centuries of settling and the gradual encroachment of vegetation. It is partially overgrown now, as many such monuments are, the burnt and fragmented material beneath the surface still holding the residue of ancient hearth fires. The kidney or horseshoe shape is characteristic of the type, formed naturally as spent stone accumulated around three sides of a central trough. Fulachtaí fia tend to cluster near water sources, and the stream alongside this one would have been as essential to its function as the fire itself.