The stone, known to researchers as Monaincha 3, was lost before 1878, meaning it disappeared sometime between its first recorded observation and the publication of George Petrie's notes after his death in 1866. What survives is a drawing, initialled by Petrie but undated, showing a slab that measured roughly 0.78 metres by 0.48 metres, decorated with what the antiquarian Robert Macalister later described as a heart-shaped figure laid upon a saltire, that is, a diagonal cross. Below that motif ran an inscription, partially legible, that Petrie read as a prayer formula: "Pray for Dom[..]".

The inscription, in the early medieval Irish formula known as oroit ar, meaning "a prayer for", expands most plausibly to OROIT AR DO[MNALL] or possibly OROIT AR DO[NNAN], a dedication to an otherwise unidentified Domnall or Donnan. Petrie noted that the decorative design appeared to post-date the twelfth century, placing it in a period of evolving stoneworking traditions at Monaincha, a site associated with an early monastic island settlement in what was once a boggy lake. Perhaps most intriguing is what Petrie's drawing reveals about the stone's physical form: a semi-circular tenon, a projecting peg-like element, visible on one of its narrow sides. This detail strongly suggests the slab was never a standalone monument but rather a component of a larger structure, most likely the tenoned arm of a free-standing cross, the kind of high cross assembled from interlocking pieces of stone. The slab, in other words, was not the cross itself but a fragment of one, now doubly lost: first from its original setting, then from the record altogether.