It is a keystone boss, the type of carved block placed at the intersection of rib vaulting, where the arching ribs of a stone ceiling converge and lock together. This particular example measures just 18 centimetres across, yet its surface carries an intricate pattern of acorns and oak leaves carved in raised relief, the kind of decorative detail that would originally have been set high overhead in a vaulted interior, visible only to those who thought to look upward.

The fragment originates from Leggetsrath in County Kilkenny and is catalogued in the depot's stone carving collection as KD003. The overall stone measures 44 centimetres in length and up to 24 centimetres in height, with the ribs extending outward from the central boss. One side of those ribs has broken away, leaving the stone in a partial state that makes it easier, in a way, to read its construction. Stylistically, the floriated carving places the piece in the 13th century, a period of significant ecclesiastical and Anglo-Norman building activity across Kilkenny, when sandstone was a common local medium for decorative stonework. The choice of oak leaves and acorns as a motif is consistent with Romanesque and early Gothic decorative traditions in Ireland and Britain, where natural foliage frequently appeared alongside more formal geometric or figural schemes.

The stone is not on public display, held instead in storage, which means the fragment exists largely outside the usual circuits of visibility. What survives is a small, precise piece of craft, separated from whatever ceiling or doorway once gave it context, the building itself long gone or unidentified.