It came to light not through deliberate excavation but as an incidental discovery during monitored groundworks for the Lough Mask Regional Water Supply Scheme in 2001 and 2002, when the northern edge of the feature was exposed along the edge of a pipeline corridor. The bulk of the mound, around ten metres in diameter, remained intact beneath the adjacent ground. Rather than proceed as planned, the engineers rerouted the pipeline entirely to leave the monument untouched.

A charcoal sample taken from the mound was radiocarbon dated to 3955 plus or minus 45 BP, placing its use somewhere between 2580 and 2300 BC, in the Late Neolithic period. Burnt mounds of this kind are among the most common prehistoric monuments in Ireland, typically formed from the repeated heating of stones in fire and their subsequent dumping after use, often in connection with water-based cooking or processing activities. What makes the Treannaskehy site particularly interesting is its context within the immediate landscape: another burnt mound lies approximately 120 metres to the north-east, and a fulacht fia, a related type of site also associated with burnt stone and water, sits around 100 metres to the south. A fulacht fia generally consists of a horseshoe-shaped mound surrounding a trough, thought to have been used for heating water by dropping fire-heated stones directly into it. The clustering of three such monuments within a small area of otherwise unremarkable flatland suggests that this corner of Mayo saw sustained, repeated activity across prehistoric communities, even if the precise nature of that activity remains a matter of ongoing discussion among archaeologists.