Buried beneath the surface of a large arable field near Thomondtown, the ghostly outline of an ancient enclosure emerges twice a year as a cropmark, that is, a variation in the colour and growth of crops or grass caused by buried archaeology affecting the soil's moisture and nutrient levels differently from the surrounding ground. Depending on the season, it appears either as a positive cropmark, where the vegetation grows more vigorously over the buried feature, or as a negative one, where it grows less so. Satellite imagery captured on 12 July 2013 and again on 2 June 2016 recorded both variations.

What the imagery suggests is a subcircular enclosure with external diameters of approximately 35 metres on the northeast to southwest axis and around 32 metres northwest to southeast, defined by a bank roughly 2 metres wide. Enclosures of this general form are common across Ireland and can date to anywhere from the Bronze Age through to the early medieval period, often interpreted as the remains of a rath or ringfort, the type of enclosed farmstead that once dotted the Irish countryside in considerable numbers. Notably, there is no clear evidence of an entrance gap through the bank, which makes interpretation cautious. The enclosure sits approximately 1.2 kilometres southeast of the Gracedieu ecclesiastical complex, a cluster of early religious monuments recorded under the reference DU007-015001 to DU007-015010, and around 69 metres north of a small unnamed stream running west to east. The record was compiled by Tom Condit and uploaded in April 2021.

Because the feature has no surface expression, there is nothing to see at ground level. The field appears, to all outward appearances, entirely ordinary. The best way to observe the enclosure is through Google Earth, where the cropmark imagery from 2013 and 2016 remains accessible. For those who do visit the area in person, the surrounding landscape near Gracedieu rewards attention, given the concentration of ecclesiastical remains nearby, though the enclosure itself remains, for now, a feature legible only to satellites and the slowly differentiating crops above it.