Known in Irish as Oileán an Teampaill, the island holds an oratory, a cemetery, a stone enclosure, cross-slabs and an ogham stone, all packed into a space not much larger than a suburban garden. What makes it genuinely unusual is that it preserves two distinct phases of religious settlement, one built entirely in wood, the other replacing it stone for stone on the same footprint, as if the later community were consciously honouring the layout of the one that came before.

Before excavations were carried out under the direction of M.J. O'Kelly in 1955 and 1956, only the stone oratory, a cloghaun (a small corbelled stone structure), and traces of an enclosing wall were visible above ground. What O'Kelly uncovered was considerably more complex. The earliest phase included a circular wooden hut near the centre of the island, with evidence of a pit furnace, animal bones, and shells in its occupation layer, alongside a small rectangular wooden oratory evidenced by five post-holes and measuring roughly 3 by 2 metres. To its north and northwest lay a cemetery of at least thirty-three burials, mostly simple dug graves, all aligned with the wooden oratory. In the second phase, a stone oratory was raised on the exact site of the wooden one, the wooden hut gave way to a circular stone house equipped with an annulus and a water cistern, and eventually a drystone enclosure wall was built around the whole habitable surface of the island. Paved paths ran from the two entrances inward toward the oratory. An ogham-inscribed cross-slab, two stone crosses, a shrine, and two further cross-slabs were also recovered, though it remains uncertain which phase they belong to. The site had previously been misidentified by the scholar O'Hanlon in 1872 as the monasterium Ibracense, a monastery in Munster attributed to St Malachy and founded around 1127, an error that persisted until the excavations settled the matter.

The island can be reached on foot from the neighbouring Beginish Island along a sand-bar, but only during the vernal equinoctial tides in spring. At other times, a boat is required. A natural slope of rock on the eastern side of the island serves as a landing place.