Around its edge runs a Latin inscription that has been deteriorating for perhaps twelve centuries, and which nobody today can read with any confidence. Scholars have been arguing about what it says since at least 1840, and the current state of the lettering makes it unlikely the argument will ever be settled. A large shrub now grows in front of it, which makes things no easier.

The slab sits on Cloon Island, near Castleconnell in County Limerick, built into the ruins of a medieval church that itself occupies the high ground of the island. The stone was first recorded in 1840, when the antiquarian William Wakeman drew it for the scholar George Petrie. Petrie described it as set into the interior face of the north wall, though by 1912, when H.S. Crawford examined it, the slab was in its present position on the outer face of the west wall. Whether Petrie was simply mistaken, or whether the stone was physically moved at some point in the intervening decades, remains unresolved. The carving itself shows an equal-armed cross, sometimes called a Greek cross, set within two concentric circles, with the arms of the cross opening outward to meet the circular frame. The inscription curves around the perimeter in two arcs, with the bases of the letters oriented toward the centre. Wakeman also noted possible ogham markings, a form of early medieval script using a series of notches and strokes along a central line, on the right-hand side of the stone. R.A.S. Macalister, writing in 1949, proposed reading the Latin inscription as "LOBED FECET CRUCE[M]", meaning roughly "Lobed made the cross". Okasha and Forsyth, reviewing the stone in 2001, found the surviving letters too far deteriorated to support that reading and could recover only a fragmentary sequence: "[.--][B][.][ND][--][L] | A[.][--]A". They dated the slab on stylistic grounds to a possible 8th-century origin.

The church ruin sits in the grounds of a private house on Cloon Island, so access requires permission. The stone itself is set 81 centimetres from the ground and positioned 69 centimetres to the south of the church doorway; even once located, the shrub growing directly in front of it will obscure part of the view. A second cross-slab is also recorded at the same church. Anyone approaching the site should bear in mind that what they are looking at is, effectively, a puzzle that has outlasted every attempt to solve it.