What gives it away is the crop itself. In the dry summer of 1989, an aerial photograph taken as part of a county-wide survey captured a tell-tale ring of differential growth in the field below, where the buried remains of a bank and outer fosse, a defensive ditch encircling the bank, caused the vegetation above them to grow at a slightly different rate to the surrounding soil. That circular shadow, roughly 25 metres across, is all that visibly remains of what was once a rath, the Irish term for a ringfort, the most common type of early medieval settlement in the country.

Ringforts are typically dated to between the sixth and tenth centuries, and most were the enclosed farmsteads of individual farming families rather than military fortifications in any formal sense. The enclosing bank and fosse would have defined a household's space, kept livestock in, and offered a degree of social as well as physical boundary. The one at Shanballymore belongs to the smaller end of the scale at around 25 metres in diameter, suggesting a modest holding. Its bank has been levelled entirely, most likely through centuries of agricultural use, leaving only the fosse's ghost pressed faintly into the subsoil. Sites like this one are sometimes described as levelled precisely because nothing protrudes above the surface; they survive not as earthworks but as archaeology, detectable only through techniques such as aerial photography or geophysical survey.