Illaunloughan, known in Irish as Oileán Lócháin, is low-lying and easily overlooked against the broader drama of the Iveragh peninsula. Yet excavations carried out over four seasons between 1992 and 1995 uncovered something quietly absorbing on its western shore: a circular early medieval hut, about 3.7 metres in diameter, whose walls were formed not from the usual dry-stone construction but from two shallow parallel trenches cut through the bedrock, filled with a sod core held in place by post and wattle revetment. A paved path led to an east-facing entrance just 1.3 metres wide, and inside, a rectangular stone-kerbed hearth occupied the centre of the floor. Charcoal from that hearth was radiocarbon-dated to between AD 640 and 751, placing occupation firmly in the early Christian period.

The island's name gives almost as much to puzzle over as the archaeology. There is no historical documentation for it, and whether Lócháin refers to a saint, perhaps one of the two Lochans mentioned in the Martyrology of Oengus, written around AD 800, or simply means something closer to "island of the chaff", remains unresolved. The saint theory is lent some weight by the existence of Killoughane, an ecclesiastical site at the eastern end of the Iveragh peninsula, whose name carries the same element. On the island itself, a possible ecclesiastical enclosure lay adjacent to the two conjoined hut sites, and may have pre-dated them or been in use at the same time. Alongside the hut remains, excavators recovered a puzzling grooved stone from the trench fill: a rounded beach stone in grey fine-grained sandstone, bearing three deep, smooth grooves whose arrangement superficially resembles an ingot mould used in metalworking, though it is smaller, incomplete, and shows no evidence of rope or cord wear. Its function was never established.