A clochán is a dry-stone beehive hut, built without mortar, its corbelled walls leaning gradually inward until the courses close into a dome overhead. The monks of the early medieval monastery on this Atlantic rock off the Kerry coast built several of them, and the one known as Cell B gives a clearer sense of the craft involved than almost any description can quite prepare you for.

Cell B sits on a stepped platform that rises up to 1.7 metres above the paved terrace to its south-east, and appears to overlie the foundation courses of an earlier structure, Cell A, to its south-west. A curved flight of steps on the south side provides access to a level strip of ground running behind Cells B, C, and D. Inside, the flagged floor measures 2.9 metres by 2.8 metres and slopes slightly downward toward the doorway, which is 1.3 metres high and tapers as it rises, narrowing from 0.61 metres at the base to 0.47 metres just under the head. Two niches are set into the walls, and an internally projecting slab sits 0.95 metres above floor level, likely used for storage or perhaps to support a shelf. The dome, its exterior restored, is sealed at the top by a large slab and reaches an internal height of 3.15 metres, which is considerably more generous than the footprint alone might suggest. That combination of a compressed floor area and a soaring corbelled ceiling gives the interior an almost counter-intuitive quality, cramped and spacious at the same moment. These precise figures were recorded by O'Sullivan and Sheehan in 1996, and they remain the most detailed account of the structure's dimensions and internal arrangement.