Somewhere beneath or just above its surface, a crannog survives, recorded but little discussed. A crannog is an artificial or partially artificial island, typically constructed from layers of timber, stone, peat, and brushwood, built out into a lake to create a defensible dwelling place. They were in use in Ireland from the Bronze Age well into the early medieval period, and some continued to be occupied or modified as late as the seventeenth century.

Lough Mask itself has a complicated geology, sitting above a karst limestone landscape riddled with underground drainage channels. The lake has no conventional surface outlet; its waters drain away through fissures in the rock and resurface at Lough Corrib. This same landscape made the area strategically and agriculturally significant for centuries, and the presence of a crannog here is consistent with a wider pattern of lake-based settlement across the west of Ireland. Without more detailed records presently available for this particular site, its date of construction, the nature of any structures built upon it, and its history of occupation remain uncertain.