It is not. Beneath the vegetation lies a spread of burnt material, the accumulated debris of a fulacht fia, a type of prehistoric cooking site found in considerable numbers across Ireland. The name, sometimes rendered as fulacht fiadh, refers loosely to a cooking pit of the ancient hunter. The typical arrangement involves a trough, usually lined with timber or stone, filled with water and heated by dropping fire-cracked stones into it until the water boiled. Those spent, shattered stones were then discarded to the side, building up over time into the horseshoe-shaped mounds that archaeologists now recognise across the Irish countryside.

The Knawhill mound appeared on the Ordnance Survey six-inch map of 1937, recorded simply as a mound near the river. It was noted more precisely by Bowman in 1934, who identified it as one of at least three fulachta fiadh in the same townland, suggesting that this particular stretch of the north Cork landscape, close to a reliable water source, was returned to repeatedly in prehistory for the same purpose. Whether that purpose was purely culinary, or extended to other uses such as bathing or textile processing, as some researchers have proposed for fulachta fiadh more broadly, remains an open question at this site as at many others. The proximity to the river is characteristic; these sites almost always appear beside water, which was both a practical necessity and, perhaps, part of what drew people back to the same spots generation after generation.