Look closer and it resolves into something quite deliberate: two flat slabs, one raised above the other on a pair of small pillars, the lower slab itself set on a carefully laid plinth of coursed stone. A cross has been roughly incised into the lower surface, and the upper slab carries an arrangement of quartzite pebbles and flowers. A plaque identifies it plainly as an altar of the Penal Times, with the inscription noting that Mass was said here between 1640 and 1800.

The Penal Laws were a series of statutes, enacted and enforced with varying intensity across the seventeenth and eighteenth centuries, that prohibited or severely restricted Catholic worship in Ireland. Catholic clergy were banned, churches closed, and the celebration of Mass made a punishable offence. In response, priests and congregations gathered at outdoor sites, often in remote or naturally sheltered spots, to hold services away from official scrutiny. These became known as mass-rocks, and they survive across Ireland in considerable numbers, ranging from bare fieldstone to more formally constructed altars like this one. The Curraheen example, with its coursed plinth and two-tiered construction, has a degree of permanence that suggests it was used with some regularity and known to the local community over many generations. The date range on the plaque, spanning a century and a half, reflects just how long the practice continued before Catholic Emancipation gradually made open worship possible again.