The mound is composed of burnt and fire-cracked stone, the characteristic signature of a fulacht fia, a type of prehistoric cooking or processing site found in great numbers across Ireland. The material has been accumulating, layer by layer, since someone last used this spot, possibly during the Bronze Age, and then simply walked away and left it.

A fulacht fia typically consists of a trough, often timber-lined and sunk into wet ground, which was filled with water and then heated by dropping fire-cracked stones into it. The stones, once spent, were discarded into a mound nearby. Repeated over years or generations, this process produced the horseshoe-shaped or irregular spreads of shattered stone that archaeologists now routinely identify across the Irish landscape. The Barradaw example measures roughly six metres in length, five and a half metres wide, and less than half a metre in height, modest by any measure but intact enough to be recorded. It sits adjacent to the south-western edge of a nearby enclosure, suggesting it may have been functionally connected to a broader settlement or farmstead in the area. The marshy ground surrounding the mound is not coincidental; these sites were deliberately placed near water sources, and the boggy conditions that made them useful in prehistory have also helped preserve them ever since. A field fence, running north-east to south-west, now runs directly across the top of the mound, a small indignity that nonetheless has done little to erase the underlying archaeology.