Crop marks, the subtle variations in colour and growth that appear in aerial photographs when buried features affect how plants draw moisture from the soil, are among the quieter ways the past makes itself known. In this case, the mark outlined something oval and substantial, hinting at a large enclosed space long since swallowed by centuries of farmland.

The record for this site, compiled by David O'Connor and later updated by Christine Baker, notes that the enclosure may contain internal features, though the detail of those remains unclear from surface evidence alone. A geophysical survey carried out under Licence 14R001 produced little of note, which is not unusual; such surveys measure subsurface anomalies using electrical resistance or magnetometry, and not every buried feature responds reliably to these methods. More conclusive was targeted testing under Licence 14E0007, which confirmed a ditch approximately 100 metres in diameter, 2.5 metres wide and 1.1 metres deep. That is a substantial earthwork by any measure, the kind of enclosure that in Irish archaeology tends to signal a site of some social or ceremonial significance, potentially prehistoric or early medieval in origin, though the notes stop short of assigning a period. The site was flagged for excavation in advance of development, as of the record's upload date in January 2015.

Drumnigh sits in the Malahide area of north County Dublin, a landscape that has seen considerable residential development in recent decades, which is precisely why a site like this enters the record when it does. Archaeological testing ahead of planning permission is a common mechanism by which otherwise invisible sites come to light. Whether any excavation has since taken place, and what it may have found, would require checking with the National Monuments Service or the excavation licencing records held by the Department of Housing, Local Government and Heritage. The field itself is unlikely to present anything visible to the eye at ground level, but for anyone with an interest in the buried layers beneath suburban Dublin, the story of how this enclosure was identified, incrementally and imperfectly, is instructive in its own right.