This is a fulacht fia, a type of ancient cooking or processing site found in large numbers across Ireland, typically dating to the Bronze Age. The name refers broadly to a mound of heat-shattered stone that accumulates when rocks are repeatedly used to boil water and then discarded. The presence of one here, tucked into low-lying pasture surrounded by trees and rocky terrain, is quietly telling about the long human relationship with this particular patch of ground and its pond.

What survives at Glencolumbkille consists of two distinct stone banks. The larger of the two is grass-covered, oriented roughly north-east to south-west, measuring seven metres in that direction and five metres across, and rising to about 0.8 metres in height. Beside it to the north-west sits a rougher, lower, curving bank. Taken together, these two elements suggest the original structure was horseshoe-shaped, enclosing an interior space of roughly five metres in diameter and open to the north-east. That open end would likely have faced the water source, the pond still visible today at the south-western edge of the monument. The horseshoe form is a well-recognised pattern for fulachta fiadh across Ireland, where the enclosing mound of discarded burnt stone built up gradually around a central trough or hearth area over many episodes of use.