It measures roughly four metres by four metres and rises just fifteen centimetres above the surrounding grass, easy to miss, easier still to dismiss as a natural feature of the landscape. It is, in fact, a fulacht fia, a type of prehistoric cooking site found in great numbers across Ireland. The typical interpretation is that such sites were used to heat water by dropping fire-heated stones into a trough, bringing it to a boil for cooking meat, though their exact function remains debated among archaeologists. The cracked and spent stones were then discarded into a mound, and it is those accumulated fragments that survive as the only visible trace today.

What makes this particular site more than a solitary curiosity is what lies around it. Within fifty metres, three further fulachtaí fia have been recorded: one approximately thirty metres to the south, another thirty metres to the south-south-east, and a fourth around fifty metres to the north-east. The clustering of four such sites within such a compact area suggests repeated, sustained activity rather than a single episode of use. Fulachtaí fia are generally dated to the Bronze Age, roughly 1500 to 500 BC, though some examples extend beyond those boundaries in either direction. Whether this particular cluster reflects seasonal gatherings, a permanently occupied settlement nearby, or some more specialised use of the land is not known. The mounds themselves preserve little beyond the burnt material, but their grouping at Knockballymartin gives the site an unusual density that sets it apart from the thousands of isolated examples recorded elsewhere in Cork and across Ireland.