For most of its existence, this fulacht fia in Ballynamanagh lay beneath the surface of a gently rolling field, invisible until a plough broke the ground in 1984 and brought it into view alongside two other similar sites in the same area.

A fulacht fia, sometimes called a burnt mound, is one of the most common prehistoric monument types in Ireland. The basic form involves a trough, a water source, and a large quantity of stones heated in fire and then dropped into the water to bring it to a boil, leaving behind cracked and blackened debris that accumulates over time into a characteristic horseshoe or oval shape. The Ballynamanagh example fits the pattern closely. It presents as a roughly circular spread of dark soil, approximately 11.6 metres east to west and 10.5 metres north to south, rising to about 0.4 metres in height. Within that spread, two concentrations of small fire-fractured stones flank a central area of fine dark-grey clay that is notably free of stone. A stream, now channelled, runs around 120 metres to the west, which would have provided the water supply that any such site requires. About 10 metres to the south, a separate patch of similar dark clay measuring roughly 2 metres across was also recorded. It may represent a hearth associated with the main site, though no charcoal was found to confirm that reading.