The mound almost certainly marks the site of a fulacht fia, a type of prehistoric cooking place found in enormous numbers across Ireland. The typical arrangement involved heating stones in a fire, dropping them into a water-filled trough to bring it to a boil, and using that heat to cook meat. Over time, the cracked and spent stones accumulated into the characteristic horseshoe or oval mound that survives in the landscape long after everything else has vanished. Ireland has thousands of these sites, mostly dating to the Bronze Age, and they cluster reliably near sources of running water, which made the Knockilly mound's position beside a stream exactly what the pattern would predict.

The site appears on the Ordnance Survey six-inch map produced in 1937, recorded as a circular mound, which is how it entered the archaeological record. Beyond that cartographic fact, the details are sparse, and for a particular reason: when researchers attempted to examine the site directly, permission to inspect it was refused. The mound therefore remains documented at a distance, its precise condition, dimensions, and state of preservation unconfirmed by any modern ground survey. That refusal draws a small curtain over what might otherwise be a routine entry, leaving the site in a kind of suspended state, acknowledged but unexamined, present on maps but closed to scrutiny.