It is a fulacht fia, a type of site found in enormous numbers across Ireland, and one of the more quietly puzzling features of the prehistoric landscape. The term refers to a mound of fire-cracked stone, typically horseshoe-shaped, built up over centuries of repeated use around a water trough that was heated by dropping fire-heated stones into it. What they were actually used for, whether cooking, bathing, brewing, or something else entirely, remains a matter of genuine archaeological debate.

The Ballyleigh site appears on a 1940 Ordnance Survey six-inch map, where it is recorded as a mound lying to the south of a stream, the proximity to water being entirely typical of such sites. Fulachtaí fia are almost always found near a reliable water source, which would have been essential to whatever process was being carried out. The spread of burnt material noted at Ballyleigh is the characteristic signature of these sites: thousands of stones, heated in fire and then plunged into water to raise its temperature, crack and shatter with use and are discarded into a growing midden of blackened debris. Over time, that refuse builds into the low, dark mound that makes these sites recognisable. Most fulachtaí fia in Ireland date to the Bronze Age, roughly 2000 to 500 BC, though some continued in use into later periods.