It measures somewhere between six and eight metres in length, four metres wide, and rises to between one and a half and two and a half metres in height, making it less a slab than a substantial geological presence in the landscape. According to local tradition, this was once a mass-rock, a flat or table-like stone used as a makeshift altar during the Penal era, when Catholic worship was suppressed under laws that banned priests from practising openly. Congregations would gather in remote or out-of-the-way places, often with a lookout posted, to attend Mass said in secret.

The site carries a quiet double function. Beyond its religious history, the stone forms part of the boundary of an enclosure located immediately to the south-east. This suggests the landscape here has been shaped and used across multiple periods, with the rock serving structural as well as ceremonial purposes. The enclosure and the mass-rock are bound together in the same modest arrangement of stone and hillside, each lending the other a little more context. That a community would choose such a prominent natural feature for clandestine worship makes a certain practical sense: the elevated, open ground of a mountain slope offers visibility in all directions, useful when the gathering itself was a criminal act.