At the medieval parish church of Seskinan at Knockboy in County Waterford, an ancient inscribed stone sits not in a display case or on a plinth but built directly into the fabric of the building, functioning as the inner lintel of the upper window in the west gable. It is one of seven ogham stones associated with the site, with six others re-used elsewhere in the church's structure, mostly as lintels. Ogham is an early medieval Irish script in which letters are represented by a series of notches and scores cut along a central stem line, most commonly along the edge of a stone, and it was used primarily from roughly the fourth to the seventh centuries. The fact that so many examples ended up repurposed as building material here is not unusual for the period; early Christian and medieval builders were pragmatic about available stone, and inscribed slabs were simply useful rectangles.

The stone measures approximately 1.45 metres long by 0.38 metres wide and 0.18 metres deep. It was first identified in 1851 by G. V. du Noyer, an artist and antiquarian whose fieldwork across Ireland documented many such discoveries. The scholar R. A. S. Macalister read the inscription in 1907 as beginning CIR MAQI MUC, a partial formula that in ogham conventions typically names a person and their father or kin group, though the text appears to continue into the masonry and cannot be read in full. When Macalister returned to the site in 1938, he found the west wall obscured by what he described as a dense mass of ivy, which had entirely hidden both the stone and its inscription. How much remains legible beneath the surface of the wall is still uncertain, with the possibility of further scores and notches embedded in the surrounding structure.

The stone has since been examined as part of the Ogham in 3D project run by the School of Celtic Studies at the Dublin Institute for Advanced Studies, an initiative that uses three-dimensional scanning to document ogham inscriptions in detail, making it possible to read weathered or partially obscured texts that would otherwise be difficult to study. Whether the full extent of this particular inscription can be recovered through that method remains an open question, but the work at least preserves what survives.