A cashel is a dry-stone circular wall, typically used in early Christian Ireland to define and protect a monastic or ecclesiastical site, and the one recorded here had a name of its own: Caissel Irra. That specificity, a named cashel rather than an anonymous field boundary, suggests this was a place of some local significance, though the dunes have done a quiet job of obscuring whatever evidence once remained.

The historian T. O'Rorke noted in 1890 that the church at Killaspugbrone had been constructed within the bounds of Caissel Irra. More than half a century earlier, the Ordnance Survey Letters of 1836 recorded a Reverend Mr. Connolly observing that the cashel could still be seen enclosing the church at that time. The gap between those two accounts is telling: by O'Rorke's era the enclosure was already a matter of historical record rather than visible fabric, and the creeping sand dunes of the coastline appear to have continued their work in the years since. The church itself, dedicated to a bishop saint whose name survives in the place name Killaspugbrone, occupies a site with considerable early Christian associations, but the enclosing cashel that once gave it its formal boundary has largely disappeared from view.