A mass-rock once stood here, one of the improvised outdoor altars used by Catholic priests to celebrate Mass covertly during the Penal Law era, when the public practice of Catholicism was suppressed under British legislation. These were not purpose-built structures but often simply large flat stones in remote or sheltered spots, chosen for their concealment as much as their convenience. The Corruragh example has been entirely erased by land reclamation, leaving no visible trace in the field.

Alongside the mass-rock there was also a cross-inscribed stone, a slab or boulder bearing an incised cross, the kind of simple devotional carving found at many early Christian and later religious sites across Ireland. That stone survived, though not in place. At some point during or after the land reclamation work, it was lifted and set into the wall of a farm building roughly 400 metres to the north-east, where it remains. The mass-rock itself was not so fortunate. Local knowledge preserved the memory of both features long enough for them to be recorded, but the rock itself is gone.