This is a fulacht fia, a type of prehistoric cooking or heating site found in considerable numbers across Ireland, typically Bronze Age in origin. The usual interpretation is that large stones were heated in a fire and then dropped into a water-filled trough to bring it rapidly to the boil, leaving behind a crescentic mound of cracked and fire-reddened stone that can survive in the landscape for thousands of years.

The mound at Lecarrow measures roughly 7.7 metres on its northwest to southeast axis and about 5.2 metres across, opening to the east-northeast in the direction of the stream, which would have provided the water supply essential to its function. The two arms of the horseshoe are notably unequal. The northern arm is the more prominent of the two, and burnt stone is still visible on its surface, a direct trace of whatever activity took place here. The southern arm is lower and less clearly defined, and its eastern tip has been cut across by a later earthen field bank, so the original shape of the monument has been partially obscured. A slight saddle between the two arms at the southeast marks the point where both mounds fade gradually into the surrounding ground. One set stone, about 25 centimetres long, is visible on the north-eastern side at the base of the northern arm, and may be a remnant of an external revetment, a facing of stone used to hold the mound in shape, though its relationship to the original structure is uncertain. The site sits on a gently sloping, northwest-facing flank that forms part of the flood plain of the Pollbrandy stream, a location entirely typical of fulachta fia, which were almost invariably sited close to running water.