Beneath the turf lies a spread of burnt material roughly twenty-two metres long and ten metres wide, the characteristic calling card of a fulacht fia. These are among the most common prehistoric monuments in Ireland, thought to date mainly from the Bronze Age, and the working theory for most of them is that they functioned as cooking sites: stones would be heated in a fire, dropped into a trough of water to bring it to the boil, and used to cook meat. The burnt and shattered stones, discarded repeatedly over time, accumulated into the horseshoe-shaped or oval mounds that survive today.

What makes Propoge quietly notable is not any single feature of this mound but the fact that it is not alone. Two further fulachtaí fia lie within a short distance, one approximately a hundred and fifty metres to the south and another around a hundred metres to the southwest. Three such sites clustered within the same general area suggests repeated or prolonged activity in this landscape during prehistory, perhaps indicating a favoured location near water, since fulachtaí fia are almost invariably found close to a stream, spring, or boggy ground that would have supplied the necessary water for the trough.