A large stone, just over two metres tall, was at some point repurposed as a corner-stone in the ruins of Legan Castle, pressed into service as a building block. It has since been retrieved and now stands upright by a doorway, which is a considerably more dignified arrangement for an object that almost certainly predates the castle by many centuries.

The stone carries an ogham inscription, ogham being the earliest form of writing in Ireland, rendered as a series of notches and strokes cut along the edge of a stone, typically recording a personal name in an archaic form of Irish. This particular example is also cross-inscribed, a combination that often suggests the stone was reused or venerated during the early Christian period. The inscription itself is deeply worn, and scholars have disagreed about what it actually says. R. A. S. Macalister, writing in 1945, read it as LOBB[I] K[OI] MAQQI MUC[COI] [RI]N[I], a formula of the type common in ogham epigraphy, where MAQQI means "son of" and MUCCOI indicates tribal or kin affiliation. Damian McManus, reassessing it in 1997, was far more cautious; the worn surface allowed him to confirm only scattered fragments, represented as [..]LL[..][....]MAQQ[..]m[..]C[...]. The gap between those two readings says something honest about how much of the early Irish record is genuinely uncertain, suspended between what the stone once said and what time has left us to work with.