The hollow is a bullaun, a term for a rounded depression ground into a boulder or slab, typically circular, and found at ecclesiastical sites, holy wells, and other places of ritual significance across Ireland. Their precise purpose is still debated; they may have been used for grinding, for holding votive offerings, or for water blessed by association with a sacred site.

At Cloon, two bullauns rest on the same leacht. The second of these is a modest but specific object: roughly 63 centimetres by 60 centimetres, with a circular depression about 32 centimetres across and at least 9 centimetres deep. At some point, a large spall, a fragment, has broken away from its lower portion, leaving the stone slightly diminished but still legible as what it is. The dimensions were recorded by A. O'Sullivan and J. Sheehan as part of their archaeological survey of the Iveragh Peninsula, published by Cork University Press in 1996, a systematic effort to document the remarkable density of early monuments across South Kerry.