A souterrain is an underground passage or chamber, typically constructed during the early medieval period and associated with nearby settlement. Whoever repurposed these inscribed slabs either had little regard for the writing on them or, more likely, was working with whatever stone lay to hand, centuries after the original meaning of the inscriptions had faded from local memory.

One of the fifteen, a clayslate slab measuring four and a half feet in height and roughly a foot and a quarter by nine inches in cross-section, carries an inscription chisel-cut along its dexter angle, that is, the right-hand edge as the stone faces the reader. Worn but still legible, the text was read by R. A. S. Macalister in 1945 and again by Damian McManus in 2004, both arriving at the same reading: ERCAIDANA. Ogham is an early medieval script in which letters are represented by a series of strokes or notches cut along a central stemline, most often the edge of a standing stone. The name ERCAIDANA likely commemorates an individual, as is typical of Irish ogham inscriptions, which frequently record a person's name in the genitive case alongside a statement of lineage. This particular stone is now held on permanent display in the Stone Corridor at University College Cork, where it joined a significant collection of ogham stones assembled there over many decades.