But not every cross here announces itself. One rough slab, modest in both scale and ambition, stands close to a natural rock shelter in the area known as Christ's Valley, and it is easy to imagine it being passed without a second glance.

The slab is just under a metre tall, 36 centimetres wide, and barely more than a centimetre thick at 11 millimetres. On its southern face, someone has grooved a Latin cross into the stone, the lines cut simply and without ornament. A Latin cross, as distinct from the equal-armed Greek cross, has a longer vertical shaft descending below the crossbar, a form familiar from early Christian devotional practice throughout Ireland and beyond. The workmanship here is rough rather than refined, which is not unusual for Skellig Michael; the island's monks were not working in a tradition of decorative stonecutting but of austere functional piety. The slab sits near the natural shelter of Christ's Valley, a topographic name that suggests the spot held specific devotional meaning within the monastic community, though quite what rituals or prayers were associated with it is no longer known.