The structure itself is modest but carefully made, with a semicircular back wall reaching just over a metre high and roughly a metre wide, the stonework holding the hillside at bay while water finds its way northward and out.

The well is identified by the scholar O Murchadha, writing in 1967, as St. Mary's, distinguishing it from a second holy well dedicated to St. Brigid that lies a short distance to the south-east. The practice most associated with such sites is the "rounds", a devotional circuit made around the well, often on a saint's feast day, involving prayer, sometimes barefoot walking, and the leaving of small offerings. By the time the local writer O'Leary noted the well in 1919, he observed that the number of people making rounds had already diminished considerably, a decline that appears to have continued. The well is now disused, its ritual life having quietly wound down at some point in the twentieth century, leaving only the stonework and the steady seep of water as evidence of what once drew people here.

The proximity of two named holy wells in the same small area is itself worth remarking on. St. Brigid's wells are among the most numerous in Ireland, the saint's feast day on the first of February marking the beginning of spring in the older agricultural calendar. St. Mary's wells are somewhat less common in the Cork landscape. That both exist within close reach of one another at Knocknagore suggests the area once carried a degree of local devotional significance that the current quiet of the glen gives little hint of.