It exists, as far as anyone can tell from ground level, as nothing more than a slight difference in soil moisture and plant growth, the kind of subtle variation that only becomes legible from several hundred metres in the air.

The enclosure came to light through aerial imagery, specifically photographs taken via Google Earth on 10 July 2018. What they revealed was a cropmark, roughly circular in shape and approximately 23 metres in diameter. Cropmarks form when buried features such as ditches, walls, or pits affect the growth of surface vegetation above them; a filled-in ditch, for instance, retains more moisture than the surrounding subsoil, producing a line of lusher, slightly darker crops that becomes visible from altitude, particularly during dry summers when the contrast is sharpest. The circular form visible at Derrymore is consistent with a ringfort or similar early medieval enclosure, though without excavation, nothing can be said with certainty about its date, function, or the people who built it. The find was brought to attention by Jean-Charles Caillère and subsequently recorded formally in 2019.