It measures roughly nine metres north to south and thirteen metres east to west, rising about a metre from the surrounding ground, with a shallow depression hollowed into its western half. To an untrained eye it might read as a natural rise in the land, or a dumping place for field clearance. In fact it is a fulacht fia, a type of prehistoric cooking site found in enormous numbers across Ireland, and this one sits within a cluster of five such monuments in Kilnahulla More alone.

A fulacht fia, in the most straightforward terms, is an outdoor cooking place used during the Bronze Age, typically consisting of a trough, a hearth, and a mound of fire-cracked stone. The process involved heating stones in a fire and dropping them into a water-filled trough to bring it to a boil, with the shattered, spent stone gradually accumulating into the characteristic horseshoe-shaped or irregular mound that survives today. The depression visible in the western half of this mound most likely marks where the trough once sat. What makes Kilnahulla More quietly interesting is not any single monument in isolation but the density of them, five fulachta fiadh within a small area beside a stream, suggesting repeated, perhaps seasonal, use of this particular stretch of water over a long period. The proximity to running water was no accident; a reliable source was essential to the whole process.