But step close and the stone reveals itself to be something altogether more considered: a pillar worked into a roughly cruciform shape, its two faces carrying different decorative programmes of considerable sophistication for an object of such modest dimensions.

The east face presents a large Latin cross in false relief, a technique in which the background is cut away to leave the design standing proud of the surface, with prominent T-shaped terminals at the arms. Where the arms meet the shaft, a roundel marks the junction, and the base of the cross terminates in a pair of opposed angular spirals, a motif with deep roots in early medieval Irish stonework. Small bosses, each with a central hollow, occupy the upper cantons, the corner spaces between the arms, with possible conjoined boss features in the lower cantons too. The west face is equally busy. Here another Latin cross in false relief sits within a broken semicircular band, its terminals subrectangular and stepped, and the junction of arms and shaft contains a rectilinear recess housing a further hollowed boss. Below the cross, a large triquetra knot, a three-cornered interlaced figure associated across early Christian Europe with ideas of unity and the divine, fills the remaining space. The scholar Higgins, writing in 1987, described the whole object as a pillar that has been worked to look vaguely cruciform, the arms projecting only slightly from the sides, which is itself an unusual approach, somewhere between a simple upright slab and a fully shaped cross.

St Macdara's Island is accessible only by boat, and the slab sits close to the shore where visitors come ashore, making it among the first things encountered on arrival. A second cross-slab, this one recumbent, lies roughly six metres to the north, so the two stones together form a small but dense concentration of early medieval carving in a remarkably exposed Atlantic setting.