This is a fulacht fia, a type of monument found in considerable numbers across Ireland, typically dating to the Bronze Age. The basic principle was simple: stones were heated in a fire and dropped into a water-filled trough, bringing the water to a boil quickly enough to cook meat. The stones crack and blacken with the repeated heating and cooling, and over time the discarded fragments accumulate into the characteristic low, spread mound that survives at sites like this one.

What makes Knocksmall quietly interesting is the proximity of a second fulacht fia, located roughly a hundred metres to the east. Two such sites sitting so close together raises questions about how this landscape was used and by whom, though the record offers no firm answers. The site itself lies on an east-facing slope, now in tillage, with marshy ground stretching away to the south and south-east. That marshy ground is not incidental. Fulachtaí fia are almost invariably found near reliable water sources, and the wet, low-lying ground nearby would have made this spot well suited to the purpose. The spread of burnt material here is described as large, suggesting sustained or repeated use rather than a single occasion.