The slab, originating from the early Christian island site of Monaincha in County Tipperary, no longer exists as a single object. Most of it has been lost entirely, and what remains sits in the basement store of the British Museum, catalogued under registration number 86/5-10.1, far from the boggy ground where it was first found.

The stone's fragmented history is almost as interesting as its inscription. In 1851, a police constable from Roscrea named Mr Waters made a drawing of it and sent that drawing to the scholar George Petrie. By 1869, when the antiquarian Margaret Stokes drew it again, the slab had already been removed to the house of the local landowner. At some point after her visit, the middle and left portions disappeared. The surviving right portion was presented to the British Museum in 1886 by a William Birch, and there it remained, unidentified in storage, until 1996, when scholar Katherine Forsyth recognised it during a visit to the museum's basement. The inscription she examined, reading OROIT AR MAENACH UA MAELLUGDACH, belongs to a well-established early medieval Irish formula; oroit ar, meaning "a prayer for", appears on a number of commemorative slabs from this period, functioning as a permanent, stone-set appeal to those who passed and read it to pray for the named individual's soul. Petrie, working from the earlier drawings, noted that an Abbot of Roscrea named Maenach, son of Conmhach, died in AD 862, and considered whether this figure might be the same man commemorated on the stone. He concluded the identification was possible but not certain, since the patronymic on the slab, úa Máel-Lugdach, meaning grandson or descendant of Máel-Lugdach, does not straightforwardly match the "son of Conmhach" in the annalistic record. The slab itself measures 0.59 by 1.245 by 0.085 metres, though that full extent can now only be reconstructed from nineteenth-century drawings.