This is a bullaun stone, a type of carved rock found at early Christian and prehistoric sites across Ireland, typically characterised by one or more cup-shaped depressions worn or cut deliberately into the surface. Their purpose remains a subject of debate among scholars; some were likely used for grinding or processing, while others acquired ritual or devotional associations over time, with the water that collects in their hollows sometimes regarded as having curative properties.

The Kildermot example is a roughly triangular block, measuring approximately 35 centimetres by 43 centimetres, and around 22 centimetres deep. The depression cut into its top is a fairly substantial hollow, some 21 centimetres in diameter and around 8 centimetres deep, suggesting deliberate and careful shaping rather than accidental wear. That it now sits secured in concrete on a plinth, rather than resting loosely in the ground as many bullaun stones do, indicates it has been recognised and deliberately preserved within the fabric of the church, though when this was done and by whom is not recorded.