The stone in question, a tall slab measuring 2.4 metres high and originating from a site near Mountrivers in County Cork, is an ogham stone, carved with an alphabet of notches and strokes along its edges that represents one of the oldest written forms of the Irish language. That it spent years bearing the weight of people crossing the Delehinagh river, rather than standing upright in a field or churchyard, says something about how such objects were regarded once their original context had been lost.

The stone came to light around 1840, when a flourmill was demolished in the area. It was one of two ogham stones found at that time, both apparently associated with the site of a possible ringfort, the kind of enclosed circular settlement common across early medieval Ireland. How the stones had ended up incorporated into a mill structure, or simply lying nearby, is unrecorded. After its discovery, this particular stone was put to practical use as a foot-bridge over the Delehinagh river, a function it served until 1851, when it was finally erected upright beside St. Olan's holy well, where it still stands. Holy wells in Ireland are typically small freshwater springs with long associations with a local saint, and the connection here to St. Olan lends the site a devotional character that sits interestingly alongside the stone's older, pre-Christian inscription. That inscription, worn and damaged by the time the scholar R. A. S. Macalister examined it, was read by him as MADORA MAQI DEGO, a formula meaning something like "Madora, son of Dego", the standard pattern of ogham commemorative texts used to record personal names and lineage in the early centuries of the first millennium.