Known as a shadow site, it appears only in certain conditions, when low sun or cropmarks betray the buried geometry beneath a field. In this case, the outline is rectangular, with a faint trace of a fosse, or ditch, still legible along its northern side.

Rectangular enclosures of this kind are less common in Ireland than their circular counterparts, the familiar ringforts that dot the landscape in their thousands. Where a rectangular form does appear, it can sometimes suggest ecclesiastical origins, monastic boundaries, or later medieval activity, though without excavation it is impossible to say with certainty what purpose this particular enclosure served or who built it. What survives at Barrafohona is essentially a soil memory, the faint imprint of a ditch that was once dug, and later filled, leaving just enough disturbance in the earth to register from above under the right conditions.