Its most notable feature is not immediately obvious: a circular, bowl-shaped hollow worn into its upper surface, roughly thirty centimetres across and fifteen deep, perpetually collecting rainwater and whatever the seasons deposit into it. This is a bullaun stone, a type of ancient carved or water-worn boulder found at early Christian and sometimes pre-Christian sites across Ireland. The precise function of bullauns remains a subject of quiet scholarly debate, with theories ranging from grain-grinding or pigment preparation to ritual use, votive offering, and cursing rites. Many were associated with healing, and the water that gathers in them was often considered to have curative or spiritually significant properties.

The stone at Parkavonear measures roughly 85 centimetres in length, 60 in width, and 40 in height, placing it firmly in the mid-range for bullauns of this kind. It sits in close company with the medieval church whose nave wall it flanks, a spatial relationship that was probably not accidental. Early ecclesiastical sites in Ireland frequently incorporated older stones and their associated traditions rather than displacing them, and the positioning of this particular bullaun just outside the nave suggests it may have held some significance to those who used the church, whether as a practical object, a devotional one, or simply as a presence too long-established to be moved.