The mound is built not from stone or earth but from burnt material, the characteristic dark, crumbly residue of thousands of years of fire-cracked stone, and it sits on an east-facing slope where a stream rising to the west cuts straight through it, dividing it into two unequal sections.

The site is a fulacht fia, a type of ancient cooking place found in great numbers across Ireland, particularly from the Bronze Age onwards. The typical arrangement involved heating stones in a fire, dropping them into a water-filled trough to bring it to a boil, and using the hot water to cook meat or carry out other heat-dependent tasks. The cracked, heat-shattered stones were discarded after use, building up over time into the horseshoe-shaped or elongated mounds that survive today, usually near a reliable water source. At Ballinlegane, that source is still present and still active enough to have shaped the archaeology: the stream bisects the mound, leaving a northern section roughly 16 metres long and a southern section of around 12 metres, with the mound reaching a maximum height of 1.8 metres. A more recent drain runs along the southern edge, a reminder that farmers have been managing this same wet ground across very different centuries. The fact that the mound has been absorbed into the field boundary suggests it had long been a fixture in the landscape before anyone thought to record it formally.