It is a bullaun, a natural or worked hollow in a rock, roughly ten inches across and five inches deep, sitting in a stone that protrudes from beneath the roots of a large oak tree. Bullauns are cup-shaped depressions found across Ireland, often associated with early Christian sites and attributed with curative or ritual significance. Here, the water that collects in the hollow has long been credited with healing ailments, warts in particular.

The folklorist Caoimhín Ó Danachair recorded the site in 1955, noting that it had formerly been known as Tobar na gCeartach, meaning roughly "the rag well", a name that describes a once-common practice at holy wells and sacred trees across Ireland: visitors would tie strips of cloth, or rags, to a nearby tree as part of a devotional act, each rag representing a prayer or an appeal for healing. The oak beside this bullaun presumably carried many such offerings. The site is said to be dedicated to Our Lady. By the time Ó Danachair visited, formal devotions had ceased, though local memory of the well's purpose and its curative reputation had clearly persisted.

The site sits in Kilmoylan Upper, and the oak tree rooting itself around the rock is the main thing to look for. The bullaun itself is easy to miss if you are not expecting something so modest; the hollow is small, barely a handspan wide, and the rock it occupies is partly obscured by the tree's roots. There are no formal facilities or signage associated with the site. If you visit after rainfall, the hollow may still hold water, which is really the point of the thing.