It measures roughly ten metres east to west and stands nearly two metres high, its horseshoe shape opening southward, with a gap of about four and a half metres across. This is a fulacht fia, a class of monument found in enormous numbers across Ireland, typically interpreted as a site where stones were heated in fire and then dropped into a water-filled trough to bring it to a boil. The burnt and shattered stone that results was raked aside after each use, and over time these discarded heaps accumulated into the distinctive crescent-shaped mounds that survive today. The exposed burnt material along the base of this one, particularly at the north and north-west, gives a clear sense of what lies just beneath the turf.

Fulachtaí fia are among the most common archaeological monuments in Ireland, with thousands recorded nationwide, yet individual examples on upland bog like this one tend to attract little attention compared to their lowland counterparts. What makes this particular site quietly notable is its setting and its company. Another fulacht fia lies approximately forty metres to the south-east, suggesting that this stretch of Mangerton Mountain saw repeated or sustained use during prehistory, not a single isolated episode. The mountain itself rises to over eight hundred metres and is better known today for its corrie lake, the Horses Glen, than for any archaeological presence. The proximity of two monuments of the same type within such a short distance of each other, both sitting on open bog well above the valley floor, raises questions about why people were cooking, or doing whatever else fulachtaí fia were used for, at this altitude.