The cross-slab in the early Christian church on High Island, off the Connemara coast of County Galway, is not simply old; it appears to have been deliberately hidden. Small traces of plaster surviving on the altar surface suggest the slab was at some point plastered over, concealing its carved face entirely. Whether that was an act of preservation, repurposing, or something else, no one can now say.

The slab itself is made from garnet mica-schist, an irregular piece of metamorphic rock measuring roughly 76 centimetres high, 82 centimetres wide, and 12 centimetres thick. Its carved surface carries an expansional cross in relief, meaning a cross whose arms broaden toward their ends, here finished with D-shaped terminals. Within the central frame of that cross, a raised band encloses a roundel notched into a second cross form, this one with expanded, round-ended arms. Superimposed on that again is a linear cross with bar terminals, creating a layered, almost compressed composition. The lower and right terminals retain fretwork decoration, a geometric interlace pattern common in early medieval stonework, though damage to the upper and left terminals has removed whatever ornament those sections once carried. The stone was, according to researchers including White Marshall and Rourke, probably reused when it was set into the altar, meaning it had already lived at least one earlier life before being built into its current position. Fisher's 2014 study of the site documented the slab in detail, drawing attention to how much visual complexity is packed into a relatively modest piece of rock that most visitors to the island would likely walk past without a second glance.