The site only reveals itself as a cropmark, the differential growth of crops over buried ditches and disturbed soil creating faint outlines that satellite imagery can catch on the right day, at the right angle, in the right season. What appears on Google Earth images from the summer of 2018 is a double-ring arrangement: an inner circular enclosure roughly 50 metres across, defined by what seems to be a slight fosse or drain, sitting within a larger outer ring approximately 80 metres in diameter. The outer ring is not complete in the imagery; it reads clearly to the south, west, and north, but fades away entirely on the eastern side.

Archaeological testing carried out by Seán Shanahan under licence 17E0665 explored the ground immediately to the east of the inner enclosure. The excavation recovered a single pit, modest in size at around 0.6 metres across and 0.2 metres deep, but layered in a way that speaks to deliberate activity. Three distinct fills were identified, including burnt clay and a charcoal-rich soil, the kind of evidence often associated with small-scale burning episodes, perhaps domestic, perhaps ritual, though the testing did not establish a firm interpretation. The pit's position would theoretically place it within the outer enclosure, yet no physical trace of that outer ditch was found in the same area, suggesting it may have been eroded or levelled on the eastern side over time. Beyond the pit, the wider area to the northeast yielded very little in the way of archaeological material.

The Knockmullen enclosure sits on a gentle south-east facing slope, and the concentric arrangement, two ditched rings one inside the other, is a form known elsewhere in Ireland, sometimes associated with enclosed settlements or ceremonial space, though without further investigation the function here remains open. What makes this site quietly compelling is precisely its elusiveness: a place that announces itself only through the grammar of cropmarks, its true extent and story still largely unread.