It is a fulacht fia, a type of prehistoric cooking site found in enormous numbers across Ireland, typically beside a water source. The method involved heating stones in a fire, then dropping them into a water-filled trough to bring the water to the boil; the cracked and blackened stones were then discarded into a mound nearby. Over centuries, those mounds survive as low, often horseshoe-shaped spreads of dark burnt material, which is exactly what has been recorded here on the southern bank of a stream.

What makes this particular site quietly notable is not its size or isolation but its company. Two further fulachta fiadh lie in the same field, making Knockmore an unusual cluster of what are already among the most common prehistoric monuments in the Irish landscape. Fulachta fiadh are generally dated to the Bronze Age, roughly 1500 to 500 BC, though some examples fall outside that range. Their concentration beside streams is no accident; a reliable water supply was essential to their function. Whether the three sites at Knockmore represent broadly contemporary activity or accumulation across a longer stretch of time is not recorded, but their presence together in a single tillage field suggests this stretch of ground beside its stream was returned to, repeatedly, for the same purpose.