It is not especially large, standing about one and a half metres tall, but it carries something remarkable: a carved Latin cross alongside an inscription in ogham, the early medieval script in which letters are represented by groups of notches and strokes cut along a central stemline, typically along the edge of a standing stone. What makes this one quietly arresting is the condition of the cuts. Scholars who examined it noted that the edge of the stone appears to have been deliberately dressed or shaped, and that the incisions are clean, regular, and unweathered, suggesting an unusual degree of care in its making.

The stone was not discovered through any planned excavation. It came to light in 1975 during a routine clean-up of the church interior, a reminder that early medieval objects sometimes survive simply because they ended up somewhere sheltered and were left alone. The inscription reads, with one letter partially lost, [A]NM SILLANN MAQ VATTILLOGG. In ogham formulae of this period, ANM is a word meaning "soul" or "name", and MAQ means "son of", so the text commemorates a person named Sillann, son of Vattillogg. These naming conventions place the stone within the broader tradition of early Christian memorial inscriptions found across Ireland and western Britain. The purple sandstone itself is a fine-grained material well suited to the sharp, deliberate cuts the carver made. The stone has since been studied as part of the Ogham in 3D project, run by the School of Celtic Studies at the Dublin Institute for Advanced Studies, which uses digital scanning to record ogham inscriptions in precise detail.