At the entrance passage to the main terrace on Sceilg Mhichíl, the great rock rising from the Atlantic off the Kerry coast, sits a small subrectangular structure that was long classified as a leacht, a type of low devotional cairn or altar traditionally associated with early Christian penitential practice. Three stone crosses rest on its upper surface, and its sides are faced with horizontally laid slabs, all of which looks perfectly at home among the monastic remains that have occupied this island since at least the sixth or seventh century. The structure measures roughly 2.5 metres along its longer axis and 1.9 metres across, modest in scale but conspicuous in its placement just inside the passage threshold.

The assumption of early medieval origin turned out to be mistaken, or at least complicated. Subsequent excavation in the area led researchers to conclude that the structure most likely dates not from the age of the monks but from the early nineteenth century, when lighthouse personnel occupied the island. Skellig Michael received its first lighthouse in 1826, and the presence of workers and keepers on the rock over the following years left its own physical traces, some of them apparently borrowing the visual language of the monastic landscape that surrounded them. Whether the crosses were placed on this structure by lighthouse workers with some devotional intent, or whether they were repositioned from elsewhere on the site, the notes do not say, and the question sits unresolved.