It measures just 36 centimetres long, 32 centimetres wide, and 16 centimetres high, little bigger than a thick hardback book. What makes it quietly significant is a small oval mortice hole cut into one of its faces, roughly 13 by 9 centimetres, the kind of socket designed to receive the upright shaft of a standing cross. If that reading is correct, this unassuming fragment is a cross-base, the footing that would once have anchored a stone or timber cross in place above the ground.

Reefert Church itself is one of several early Christian monuments clustered in the Glendalough valley, a site associated with the sixth-century founder St Kevin and continuously used as a place of burial and worship for centuries afterwards. Cross-bases of this type are not uncommon in early Irish ecclesiastical contexts, where freestanding crosses marked sacred boundaries, grave plots, or processional routes within a monastic enclosure. What is notable about this particular stone is that it had not been formally recorded before Gearóid Conroy documented it in 2012, meaning it had been sitting unacknowledged in a well-visited and extensively studied landscape for an unknown length of time.