These are bullauns, shallow bowl-shaped depressions worked into stone, found widely across early medieval ecclesiastical sites in Ireland and generally associated with the religious communities that once gathered around them. Their precise function remains debated; some were used for grinding, others seem to have held water used in ritual or healing, and many became the focus of local devotion long after the communities that made them had disappeared.

This particular rock, measuring roughly 1.9 metres east to west and standing about 0.9 metres high, holds one circular hollow near its top and a second, oval hollow some 35 centimetres to the east on the same surface. It sits just ten metres north of a natural cave known locally as St Mac Duagh's Bed, part of a cluster of at least nine ecclesiastical monuments in the same sheltered enclosure. The antiquarian T. J. Westropp, writing between 1900 and 1902, noted what he described as a large bullaun in the natural rock at this location, and the outcrop here is almost certainly what he was referring to. Mac Duagh, a sixth-century saint associated with the Burren and the founder of Kilmacduagh monastery in nearby Galway, gives his name to several features in this landscape, suggesting a tradition of religious use stretching back well over a thousand years.

The site sits within a dense, overgrown area where hazel scrub has encroached across the whole complex, and all the stones are heavily mossed. Visitors approaching along the eastern rockface of Slievecarran should expect rough, sheltered terrain rather than a cleared monument, and the bullaun itself may require a close look to distinguish from the surrounding weathered limestone.