This is a fulacht fia, one of the most common yet still somewhat mysterious monument types in the Irish archaeological landscape. The term refers to a prehistoric cooking site, typically Bronze Age in date, where stones were heated in a fire and then dropped into a water-filled trough to bring the water to a boil. Over time, the heat-shattered stones accumulated into a horseshoe-shaped mound around the trough, and it is this distinctive spread of cracked, fire-reddened material that survives in the ground long after everything else has gone.

The siting of the Lisleagh example follows a pattern seen at fulachta fia across Ireland: close proximity to a water source. Springs, streams, and boggy ground appear again and again in association with these monuments, which makes practical sense given that the entire process depended on a ready supply of water. The monument here measures approximately six metres by six metres, a modest but not unusual footprint. Whether it was used for cooking meat, brewing, bathing, or some combination of purposes remains a matter of ongoing debate among archaeologists; the burnt mound itself is largely silent on the question.