The Ordnance Survey letters of 1839 caught this detail before much else was lost, also noting that the cut-stone facing of the exterior had by then been carted away entirely for use as building material elsewhere, leaving the structure to acquire its later coat of cement render.

The well is called Toberadrugh, meaning the Hermit's Well, and the hermit in question was associated with St Fiachra, whose feast day fell on the 8th of February. The corbelled roof, a construction technique in which stones are laid in overlapping courses to form a self-supporting vault without mortar, encloses a narrow interior just 2.4 metres east to west and 0.75 metres wide, with ledges along the north and south walls and two stone slabs covering the eastern portion of the well itself. The pointed doorway in the east gable, only about 1.4 metres high and 0.55 metres wide at the threshold, opens slightly wider as you step through. Crowning that same east gable is a stone finial, identified by Waldron in 1959 as originally from the apex of a 10th or 11th-century church in the nearby graveyard. It was relocated here at some point, bringing a fragment of early medieval ecclesiastical stonework to rest on a structure that was itself already accumulating centuries of pilgrim graffiti.