This is a fulacht fia, a type of prehistoric cooking site found in considerable numbers across Ireland, and one that still holds the essential physical evidence of how it once functioned: a dense mass of heat-shattered stones packed into a charcoal-rich matrix, the residue of repeated heating and quenching over many uses.

The mechanics of a fulacht fia are straightforward but effective. Stones were heated in a fire until very hot, then dropped into a water-filled trough to bring the water to a boil, allowing meat or other food to be cooked without direct flame. The broken, fire-cracked stones that resulted from this process were discarded to the sides, gradually building up the characteristic horseshoe or kidney-shaped mound that is the most visible sign of these sites today. At Larkhill, the mound measures roughly fifteen metres in diameter and reaches a maximum height of about 1.4 metres at its north-western edge. A depression approximately 2.7 metres wide, opening to the east, appears to mark the position of the original trough. The site sits beside a low-lying basin of marshy ground fed by springs and streams, which would have provided a reliable water source, a defining requirement for this kind of site.

The mound is now largely covered in trees, and field walls have been built across both the northern and south-eastern sides, layering the agricultural history of the area directly onto the prehistoric one. That combination of natural growth and later land use makes the site easy to overlook, yet the essential form remains legible beneath it all.