What eventually settled the question was not excavation or aerial photography but grass, specifically fionnán, the coarse, tufted grass that tends to grow on disturbed or elevated ground and can trace the outline of old earthworks long after every other visible feature has softened into the surrounding landscape.

A fionnán enclosure is identified by the distinctive growth pattern of this rough grassland species over buried or partially buried features, the vegetation responding to slight differences in soil depth or drainage that a casual eye would miss entirely. The site at Maulcallee was recorded in the Sites and Monuments Record in 1990 and again in the Record of Monuments and Places in 1997, each time with that hedging qualifier attached. It was only through the work documented by O'Sullivan and Sheehan in 1992 that the fionnán evidence brought the site into clearer focus, moving it from tentative to confirmed. The enclosure form itself is one of the most common archaeological features in the Irish landscape, a defined area bounded by a bank, ditch, or wall, associated variously with settlement, agriculture, or ritual use depending on the period and context.