No earthworks survive, no banks, no obvious disturbance. Yet aerial photography reveals something entirely different: a ghostly double enclosure pressed into the earth, its outlines emerging only in dry summers when buried ditches cause the crops above them to grow differently, yellowing or flourishing in patterns that betray what lies beneath. These so-called cropmarks are among the quieter surprises of Irish archaeology, making landscapes legible in ways that ground-level survey simply cannot.

At Coolcull in the townland sometimes recorded as Moyler's, the cropmarks show two distinct but related features on a south-facing slope. An inner circular enclosure, roughly 32 metres north to south and 30 metres east to west, is defined by what appears to be a wide fosse, the term used for a defensive or boundary ditch, somewhere between three and six metres across. This circular form sits within a larger rectangular enclosure measuring approximately 60 metres by 55 metres, itself outlined by fosses or ditches of similar width. The combination of a circular inner area and a rectangular outer boundary is an unusual configuration, and the relationship between the two phases, or purposes, of enclosure remains unresolved. The site was first brought to notice by Jean Charles Caillére, and the cropmarks have been confirmed across multiple aerial surveys, including Ordnance Survey Ireland images from 2000 and 2005 as well as Google Earth imagery captured in July 2021.