The hollow near its northern end is almost half a metre deep, sub-rectangular in shape, and by all appearances entirely natural. That last detail is what makes this spot genuinely curious: the feature was venerated locally as a holy well, yet the geology seems to have done the carving. Whether nature or human hands were responsible is precisely the kind of question that makes these stones worth paying attention to.

Bullaun stones are boulders, usually of considerable size, that carry one or more cup-shaped depressions, either carved or worn into the rock. They are found throughout Ireland and are frequently associated with early Christian sites, though many predate Christianity entirely. The water that collects in their hollows was traditionally credited with healing properties, and some bullauns retained active devotional use into the modern period. The Garranereagh example sits in an interesting category: a stone whose hollow appears natural rather than worked, yet which was nonetheless recognised and named as a holy well by the local community. The boulder measures roughly 1.6 metres north to south and 1.1 metres east to west, and rises only about 35 centimetres from the ground, giving it a low, settled presence in the landscape. Smaller natural hollows mark other parts of its surface, and at the southern end there is what may be the beginning of a second, worked bullaun depression, a detail that complicates any straightforward reading of the stone as purely a natural feature.

The site was recorded in December 2014 by Tony Miller, who found it in the north-west corner of a field near the ridge top. The combination of natural geology, possible human modification, and a folk memory of sacred water makes it a small but thought-provoking example of how a feature of the landscape can accumulate meaning across very different frameworks of understanding.