This is a bullaun, a type of stone bearing one or more cup-shaped depressions whose precise original purpose remains debated, though they are widely associated with early Christian and pre-Christian ritual practice in Ireland. What makes this particular example quietly puzzling is not the stone itself but where it now sits, and where it used to.

When the antiquarian T. J. Westropp visited in 1895, and again when the scholar Mason came in 1938, the bullaun was positioned near the doorway of the early church on the island, a location that would have placed it in direct contact with those entering and leaving the sacred space. A second bullaun remains embedded in the ground at that church to this day. At some point between those recorded visits and more recent surveys, this one was moved, and now rests to the north-west of a leacht, a low commemorative cairn or shrine monument associated with early Christian devotion. The stone itself is oval granite, measuring roughly 0.6 metres by 0.43 metres, with a shallowly dished face bearing an oval depression approximately 0.3 metres across. Smaller still, a conical hollow sits within that outer depression, its form noted by Dr J. Waddell. The precise function of such layered depressions is not recorded, but bullauns were often used to collect rainwater considered to have curative or sacred properties.

The stone is not difficult to find for anyone already making their way around the island's cluster of early ecclesiastical remains, which are concentrated in a relatively compact area. The leacht beside which it now rests is part of a wider assemblage of early medieval features, and the proximity of both the bullaun and the leacht to the church makes this a rewarding spot to linger if early Christian landscape is your interest. The shift in the stone's location over the course of the twentieth century adds an extra layer of uncertainty to a monument that was already, by nature, not entirely explained.