It is not. Roughly ten metres across and only about forty centimetres high, it is composed of burnt material, the accumulated debris of repeated prehistoric cooking, and it belongs to a class of monument known as a fulacht fia, one of the most common archaeological site types in Ireland yet still not entirely understood.

A fulacht fia, sometimes called a burnt mound, is the scorched and shattered residue of an ancient method of heating water. The process involved heating stones in a fire and dropping them into a water-filled trough; the stones cracked from the thermal shock and were discarded into a heap nearby. Over many uses, that heap became a substantial crescent or horseshoe-shaped mound of fire-cracked stone and charcoal. These sites are typically Bronze Age, though the practice may have continued later, and they are almost always found near water, which this example confirms. What makes the Kilbarry site particularly legible is the survival of a dried-up stream bed, now visible as a shallow fosse, or ditch-like depression, curving around the mound to the west, north, and north-east. The stream that once supplied the site has shifted or dried out, but its former course still traces the mound like a faint signature, connecting the archaeology to the hydrology that made it possible in the first place.