What survives is roughly 25.5 metres of curved earthen bank, standing no higher than 0.85 metres, sweeping from east to northwest before meeting the line of an existing field boundary to the northeast. On its own, a bank of that modest height barely interrupts the eye. But its curve is deliberate, and its age is considerable.

Enclosures of this kind are among the most common yet least understood monument types in the Irish landscape. They were built across a long span of prehistory and the early medieval period, serving variously as farmsteads, animal enclosures, or the defended boundaries of small settlements. Without excavation it is rarely possible to say which function applied in any particular case, and Mossgrove is no exception. What can be said is that the arc at Mossgrove once formed part of a complete or near-complete circuit, the remainder either robbed out, ploughed away, or absorbed into the field system that now overlays it. A field fence running southwest cuts straight through the interior, dividing what was once a unified enclosed space into two unequal halves, a reminder of how thoroughly later agricultural practice can reorganise an ancient form without entirely erasing it.