It is roughly circular, about thirteen metres north to south and fifteen metres east to west, and rises only half a metre from the surrounding ground. Part of its surface is scattered with stones displaced by drainage works. Nothing about it announces itself. And yet it is the residue of a fulacht fia, one of the most common and least understood monument types in the Irish archaeological record.

Fulachta fia are found in their thousands across Ireland, most of them dating to the Bronze Age, roughly between 1500 and 500 BC. The typical form is a horseshoe-shaped or circular mound composed of fire-cracked stone and charcoal, the debris left behind after repeated episodes of heating stones in a fire and dropping them into a water-filled trough to bring the water to the boil. What exactly that boiling water was used for remains debated: cooking meat is the traditional explanation, but brewing, hide preparation, and even bathing have all been proposed. Whatever the purpose, the process was the same, and it left behind a distinctive dark mound of shattered, heat-fractured stone. The example at Glancam fits this profile closely, its low profile and burnt material consistent with the accumulated waste of many such sessions over an extended period.