This is a fulacht fia, a type of prehistoric cooking site found in enormous numbers across Ireland, typically identified by a horseshoe-shaped mound of fire-cracked stones deposited beside a water source. The stones would have been heated in a fire and then dropped into a trough of water to bring it to the boil, the cracked and spent stones discarded into the characteristic mound that survives today. What makes Ballyhoolahan unusual is not the presence of one such site, but the sheer concentration of them.

A researcher named Bowman, writing in 1934, recorded no fewer than nineteen fulachta fiadh within this single townland, a density that points to sustained, repeated use of this landscape over a long period. The site in question sits immediately to the west of a spring, now drained, which would once have provided the water supply essential to the process. A further possible example of the same type lies roughly 250 metres to the north-east, suggesting the area held particular appeal for whoever was using these sites, whether for cooking, processing hides, or other purposes that archaeologists continue to debate. Fulachta fiadh are most commonly dated to the Bronze Age, though some were in use earlier or later, and their precise function, long assumed to be straightforwardly culinary, has attracted considerable fresh scrutiny in recent decades.