The only way to see it is from above, and only under the right conditions: when crop growth is uneven enough to betray what lies beneath, the outline of a fosse, a roughly oval ditch measuring around 38 metres on its north-east to south-west axis and 33 metres across, emerged clearly in satellite imagery captured between 2004 and 2006. A fosse is simply a ditch, often dug to define or defend an enclosed space, and here it has left just enough of an impression in the soil to influence how crops grow directly above it, producing what archaeologists call a cropmark.

What makes the site more interesting is its context. The enclosure does not sit in isolation. A second enclosure lies roughly 65 metres to the north-east, and a ringfort, a type of circular enclosed farmstead common across early medieval Ireland, sits approximately 110 metres to the south-west. The clustering of these features across a relatively small area suggests that the landscape around Knocktopherabbey was, at some point, meaningfully organised, with different enclosed spaces serving different purposes in reasonably close proximity to one another. Whether the enclosures and the ringfort are broadly contemporary or represent activity from different periods is not something the cropmark evidence alone can resolve.