It measures roughly six metres along its longest axis and just over half a metre in height, and its composition is what gives it away: the mound is made almost entirely of burnt material, the characteristic signature of a fulacht fia. These sites, found in their thousands across Ireland, are the remains of ancient cooking or heating places where stones were fired in a hearth and then dropped into a water-filled trough to bring it to a boil. The cracked, heat-shattered stones were raked out after use and piled to the side, and it is those discarded fragments, accumulating over many uses and perhaps many generations, that formed the low horseshoe-shaped or oval mounds that survive today.

The Drombohilly example sits on the north bank of its river, which has done some of the work of revealing what the mound is made of. Erosion at the south-western edge has cut into the deposit, exposing the burnt stone and charcoal-flecked matrix within. Most fulachtaí fia in Ireland date to the Bronze Age, broadly the second millennium BC, though some were used earlier or later. They tend to cluster near water for obvious practical reasons, and a riverside slope in hill pasture, away from cultivated ground, is a typical setting. The fact that this one has survived at all, even in an eroded state, in an area of rough grazing rather than improved farmland, is not entirely surprising; undisturbed upland ground has preserved many such sites that lower-lying equivalents have lost to ploughing.