It is about eight metres across, and beneath the surface vegetation lies a concentration of fractured stone fragments in black soil, capped by a thin layer of peaty material. The exact edges of the mound are hard to determine, which is characteristic of these sites; the moss and heather mark it out only because they grow differently from the surrounding field, a subtle signal that something underneath has altered the ground.

This is a burnt mound, a type of prehistoric site found across Ireland and Britain, typically dating to the Bronze Age. The conventional interpretation is that these accumulations of fire-cracked stone represent the debris from repeated heating of rocks, which were then plunged into water-filled troughs to bring the water to the boil, either for cooking, bathing, or some industrial process. The stones shatter with thermal shock and become useless for reheating, so they were discarded in growing heaps beside the trough. What makes the Steelaun site particularly striking is not so much the mound itself but its immediate company. Within the same field, at distances ranging from twenty to fifty-five metres to the north-west, there are two further burnt mounds and a fulacht fia, the Irish term often applied to the broader class of these water-heating monuments, sometimes used more specifically for sites where a trough or cooking pit has been identified. Another fulacht fia lies roughly eighty metres to the south-south-west. The cluster suggests this low, naturally terraced shelf of land, sheltered by a ridge to the north-west and presumably well supplied with water given the field drain nearby, was returned to repeatedly, perhaps across generations or centuries, for whatever purpose these sites served.