Roughly triangular and measuring around twenty metres by fifteen, it is the larger of two islets recorded on the second edition Ordnance Survey six-inch map of 1898, and it is widely reputed to be a crannog. A crannog is an artificial or artificially enlarged island, typically constructed during the early medieval period as a defended dwelling place, built up from layers of timber, peat, stone, and brushwood. They are found across Ireland and Scotland in considerable numbers, though identifying them with certainty usually requires either excavation or at least some visible structural feature at the surface.

The problem here is that no archaeological features are visible. The island is mantled in overgrowth, and the site has only ever been inspected from the lake shore. The reputation itself was recorded as recently as 1954, when Killanin noted the island's local standing as a probable crannog, suggesting the tradition had persisted in the area long enough to be worth committing to print. Whether that tradition reflects genuine folk memory of early medieval activity, or simply the reasonable assumption that an island in a Connacht lake must once have served some human purpose, is impossible to say without closer investigation.