It was the third lintel in a souterrain, an underground stone-lined passage built beneath a ringfort at Knockshanawee in County Cork. Souterrains were typically used for storage or refuge, and the people who built this one had no apparent hesitation about repurposing an inscribed stone as a ceiling slab. Five other ogham stones were found in the same souterrain, suggesting the builders had access to a ready supply, or perhaps that the inscriptions had simply ceased to carry meaning for them.

Ogham is an early medieval Irish script in which letters are represented by notches and strokes cut along the edge of a stone, read from bottom to top. The inscription on this particular stone, which measures roughly 3.1 metres in length and 0.4 by 0.3 metres in cross-section, records a personal name and a lineage. Scholars have read it slightly differently over the decades: Power, writing in 1932, transcribed it as CUBBRIGAI MAQIMENU MAQ followed by a damaged section, while Macalister in 1945 and McManus in 2004 both preferred CULRIGAI MAQI MENUMAQ[I], the MAQI element being the ogham formula for "son of", equivalent to the later Mac. The stone has since been moved from Knockshanawee to Cork City, where it now sits at its present location, separated from the ringfort and souterrain context in which it was first recorded.