This particular mound measures roughly twelve metres along its longer axis and rises to about eighty centimetres at its highest point, with a four-metre opening facing south-east. It is a fulacht fia, a type of site found in the thousands across the Irish countryside, typically identified by a characteristic crescent or horseshoe of dark, fire-cracked stone and charcoal-rich earth, the spent material from repeated cycles of heating stones and plunging them into water-filled troughs to boil or simmer food.

The mechanics of how fulachta fiadh worked have been tested and confirmed through experimental archaeology. Stones were heated in a fire, then transferred into a wooden or stone trough sunk into the ground and filled with water; the thermal shock eventually shattered the stones, and the discarded fragments built up over time into the distinctive mound visible today. The Mountkeeffe example is not an isolated one. It belongs to a cluster of three such monuments in the immediate area, suggesting repeated or sustained activity in this particular corner of north Cork, perhaps over generations. The northern edge of the mound shows some erosion, which is common on sites that have gone unmanaged in soft, wet ground for millennia.