It is, in fact, the accumulated remains of a Bronze Age cooking site, roughly oval in shape and measuring sixteen metres from north to south and fourteen metres from east to west. The sheer ordinariness of its appearance is part of what makes it interesting.

This is a fulacht fia, a type of site found in enormous numbers across Ireland, particularly in low-lying or waterlogged ground. The typical interpretation is that these were outdoor cooking places, used by heating stones in a fire and dropping them into a water-filled trough to bring it to a boil. Over repeated use, the fire-cracked stones were discarded into a mound around the trough, and it is that accumulation of burnt and shattered material that forms the characteristic horseshoe-shaped or subcircular mounds visible today. Thousands have been recorded across the country, with particularly dense concentrations in Munster, and Cork alone holds a remarkable number of them. The Ballymountain example is a fairly typical specimen in terms of its modest height and oval footprint, the kind of site that represents not a dramatic event but generations of repeated, practical, everyday activity during the Bronze Age.