This is a leacht, a type of commemorative cairn or altar-like monument associated with early Irish monasticism, typically used as a focus for prayer or veneration of a saint. What makes this particular example quietly arresting is not its size but its position and what was found on top of it.

The leacht came to light during excavations east of the entrance to a structure known as Cell B, one of the clochans on High Island. A clochan is a drystone beehive hut, a form of monastic cell common to early Christian sites along the Atlantic seaboard. The leacht itself is modest in its dimensions, measuring 1.3 metres north to south and 0.9 metres east to west, with walls surviving to between one and three courses in height. It was constructed over the northern end of a rock-cut water trough and alongside the side-wall of a drainage channel, suggesting the builders were working carefully around existing infrastructure rather than clearing it away. In the rubble overlying the structure, excavators found a decorated cross-slab, and it is thought that this slab may originally have stood upright on the leacht itself. A second, comparable leacht was found approximately five metres to the south, hinting that such features were not isolated curiosities but part of a deliberate arrangement within the monastic enclosure.