This is a bullaun stone, a type of ancient carved rock found across Ireland, typically associated with early Christian sites though their exact purpose remains debated. Some were used for grinding, others are thought to have held holy water, and many acquired strong local traditions of healing or cursing that long outlasted whatever formal religious function they may once have served.

The stone at Brockagh was identified and recorded by Healy in 1972. The boulder measures 2.2 metres by 1.1 metres, though most of it lies beneath the surface, with only the top exposed. That visible face contains one basin, 0.34 metres in diameter and 0.13 metres deep, a depression that is modest in size but carefully formed. The fact that so much of the boulder is buried is a common feature of bullaun stones in the Irish landscape; they can appear almost incidental, easy to pass without registering what you are looking at, until you notice the deliberate hollow cut into the rock.