It measures roughly nine metres north to south, just under six metres east to west, and rises less than a metre from the ground. To a casual eye it might read as nothing more than a slight rise in the field. In fact it is a fulacht fia, one of the most common yet persistently mysterious monument types in the Irish landscape.

A fulacht fia is a burnt mound, essentially the accumulated debris of a prehistoric cooking method. The typical process involved heating stones in a fire until they were hot enough to boil water when dropped into a trough, and the cracked, fire-shattered stones were then discarded into a heap nearby. Over centuries these heaps built up into the characteristic horseshoe or kidney shape, open on one side, that archaeologists now recognise across Ireland in their thousands. At Lackaroe, the mound's opening faces east and spans roughly two and a half metres, and shattered stone is still visible on the eastern bank of the stream, likely scatter from the same activity. The monument dates broadly to the Bronze Age, though fulachtaí fia were in use across a wide span of prehistory. The stream beside it would have been essential, providing a ready water source for the whole operation.

What makes this particular site quietly interesting is its context. Immediately nearby lie the remains of a hut site and a relict field system, the faint outlines of boundaries and enclosures that once organised the land around them. Traces of a damaged field boundary run along the western bank of the same stream, abutting the mound at both its northern and southern ends. Taken together, these features suggest not an isolated episode of activity but a small, worked-in landscape, people living, farming, and cooking in the same stretch of ground above the Sheen valley, leaving behind a cluster of overlapping traces that are still, just about, readable in the grass.