The mound measures roughly five metres north to south and fifteen metres east to west, and where a drain cuts across its northern edge, a cross-section reveals burnt material to a depth of about 0.4 metres, a compact layer of charcoal, ash, and shattered stone that accumulated over repeated use.

A fulacht fia, broadly speaking, is a burnt mound thought to represent the debris from an ancient cooking or heating method, in which stones were heated in a fire and dropped into a water-filled trough to bring the water to a boil. Thousands of these sites survive across Ireland, most dating to the Bronze Age, though some have yielded evidence of earlier or later activity. The mounds build up gradually from the discarded, heat-shattered stone, which cracks and becomes useless once cooled, so fresh stone had to be used each time. The location beside a natural pond at Knockardbane fits a pattern seen repeatedly at such sites: proximity to a reliable water source appears to have been a basic requirement, whether the trough was fed directly from standing water or filled by hand. What was actually being cooked, or whether some sites served purposes other than food preparation, remains a subject of genuine archaeological debate.