Known in Irish as Carraig an Aifrinn, the rock of the Mass, this is a mass-rock, one of the outdoor sites where Catholic priests celebrated Mass in secret during the Penal Law era, when the open practice of Catholicism was suppressed under legislation that forbade Catholic worship, education, and clergy. The rock itself is modest in scale, measuring roughly 1.4 metres by 1.5 metres and rising to about a metre in height, with a broader rough ledge in front of it where a congregation could have gathered. That ledge sits around a metre above the banks of a nearby stream, providing a natural raised ground on which people would have stood or knelt.

The site sits at the foot of a north and north-west-facing slope, tucked into the eastern edge of a grass and scrub-covered rock outcrop that rises to between two and a half and three metres at its highest. A stream runs roughly five metres to the north-east. The location is deliberately secluded, the kind of sheltered hollow that offered both concealment and a degree of natural acoustics. It was recorded on the 1907 edition of the Ordnance Survey six-inch map, which suggests it was already recognised as a place of local significance by that point, a memory worth preserving in cartographic form. The scholar Ó Gallachair noted the site in 1957. Roughly fifteen metres to the north, across the stream in the neighbouring townland of Rakean, there is a megalithic tomb, a prehistoric monument likely thousands of years older than the Penal-era gatherings. The proximity of the two is probably coincidental, but it gives the valley an unusual layering of human use across very different periods.