This is a fulacht fia, one of the most common yet persistently puzzling monument types in the Irish landscape. Thousands of them survive across the island, nearly always close to water, and nearly always consisting of the same basic ingredients: a horseshoe-shaped or circular mound of fire-shattered stone, the debris left behind after repeated heating and quenching. The Lissacapia example measures somewhere between eight and ten metres in diameter and rises to between 1.2 and 1.5 metres, making it a reasonably substantial specimen, though it is heavily overgrown and sits unobtrusively in its field.

The mechanics of a fulacht fia are fairly well understood, even if the precise purpose remains debated. Water was collected in a trough, stones were heated in a nearby fire, and the hot stones were dropped into the trough to bring the water to a boil. The shattered, heat-crazed stone was then discarded in a mound around the trough, which is what survives today. These sites are generally dated to the Bronze Age, broadly spanning from around 2000 to 500 BC, and the leading theories for their use include cooking, textile processing, bathing, or some combination of all three. The Lissacapia mound follows the pattern faithfully, positioned on the eastern side of a stream, which would have provided the reliable water supply the process required.