The 1940 six-inch OS map applied that label to what is, in fact, a fulacht fia, one of the most common yet least glamorous monuments in the Irish archaeological landscape. A fulacht fia is a prehistoric cooking site, typically identified by a horseshoe or mound-shaped accumulation of fire-cracked stones and charcoal-blackened soil left behind after repeated episodes of heating water in a trough. The misidentification says something about how easy it is to misread the land when the technology for systematic survey is still developing, and perhaps also about how unassuming these monuments tend to look from the outside.

The mound at Knocknagoun is roughly circular, thirteen metres in diameter and rising to about 0.8 metres in height, its burnt material held in place by a stone revetment, a low retaining wall of stones set around the edge to keep the mound from spreading. It sits in marshy ground, which is entirely typical for this class of monument; a reliable source of water was essential to their function. What makes the location particularly notable is that another fulacht fia lies approximately thirty metres to the southeast, suggesting the area saw sustained or repeated use over time, possibly by different groups or across different periods. The two monuments are close enough to feel related but far enough apart to have functioned independently.