Illaunyregan, likely derived from the Irish for something along the lines of "little island," is recorded as the site of an enclosure, one of the most common yet persistently enigmatic categories of ancient monument in Ireland. Enclosures of this kind are typically roughly circular boundaries, formed from stone, earthen banks, or ditches, and may have served any number of purposes across a wide span of time, from early medieval settlement and farming to uses that remain genuinely unclear. That one survives on a small Clare island, separated from the mainland and its usual patterns of agricultural disturbance, makes it quietly notable.

Beyond the name of the place and the bare classification of the monument, the available record offers nothing further. No excavation notes, no recorded dimensions, no associated finds or dating evidence appear to have made their way into the accessible literature. This is not unusual for island sites in the west of Ireland, many of which were recorded in early surveys but never studied in depth. The enclosure at Illaunyregan sits in a category of places that are known to exist, marked on records, and otherwise left largely to themselves.