On the Ordnance Survey maps it is marked simply as a quarry, but according to local tradition, this hollow in the ground once served as a place of clandestine Catholic worship, a penal mass station where priests celebrated mass in secret during a period when doing so was a criminal act.

The Penal Laws, enforced with varying severity across the seventeenth and eighteenth centuries, prohibited Catholic religious practice and drove worship out of churches and into the open landscape. Congregations gathered at outdoor sites, often in natural or man-made depressions, behind hedgerows, or on remote hillsides, where the lie of the land could conceal both the priest and the people from the view of informers or authorities. A disused quarry, already a pit dug into the earth, would have offered just that kind of shelter. The site at Kilcooley appears on the 1930 edition of the six-inch Ordnance Survey map as a hachured area, meaning it was recorded as a physical feature with a raised or sunken outline, and the larger-scale OS plan surveyed between 1912 and 1916 names it as a disused quarry. It is local knowledge, passed down rather than written into any official record, that connects this unremarkable depression in a field to the practice of penal-era worship.

What survives today is essentially a landscape feature, more felt than seen, its significance carried in oral tradition rather than in stone or inscription. The undulating pastureland around it gives little away, which is perhaps fitting for a place that was always meant to go unnoticed.