The mound is barely half a metre tall and stretches roughly eight and a half metres from east to west, its curved, inward-facing side opening to the north. Easy to miss, easier still to mistake for a natural rise in the ground, it is in fact one of thousands of fulachtaí fia scattered across the Irish countryside, each one the remnant of an ancient communal hearth where water was boiled by dropping fire-heated stones into a trough. The broken, heat-shattered stones piled up around the trough over repeated use, eventually forming the characteristic horseshoe shape that survives here.

Fulachtaí fia are among the most common prehistoric monument types in Ireland, with the majority dating to the Bronze Age, broadly between 1500 and 500 BC, though some are earlier. The name itself is of uncertain and debated origin, sometimes translated loosely as "cooking place of the Fianna", though their association with any particular group is largely folkloric. The mechanics are well understood: a timber-lined trough sunk into the ground would hold water, stones heated in a nearby fire would be transferred to the trough, and the water would come to a boil within minutes. The mound at Imleach Na Muc sits in the kind of low, damp landscape that these sites typically favour, near water and away from higher, drier ground.