This is a fulacht fia, a type of site found in considerable numbers across Ireland, typically dating to the Bronze Age. The basic idea behind them is straightforward enough: a trough, usually timber-lined and filled with water, into which heated stones were dropped to raise the temperature. The cracked and shattered stones were then discarded in a horseshoe or oval heap around the trough, and it is precisely that accumulated debris which forms the mound visible today. The central depression at Ballinla is the ghost of that trough.

The mound measures roughly 10.2 metres north to south and 8.9 metres east to west, rising to just 0.6 metres above the surrounding ground. It is an unassuming presence. What makes its history slightly more legible is the 1842 Ordnance Survey six-inch map, on which the mound appears as a marked feature. By that point it had already been sitting in the field for something in the region of three thousand years. The fact that it is recorded on the 1842 map but not apparently on later revisions suggests the feature may have been partially obscured or reduced by subsequent agricultural activity, the reclamation of the marshy ground around it having altered the local landscape considerably over the intervening decades.