That alone would be remarkable enough, but this well, known locally as Lunny's Well, has accumulated so many names over the centuries that even pinning down who the saint was has defeated scholars. The Ordnance Survey Letters recorded it in 1840 under at least five variations: Tobar Mullana, Tobar Mhlunna, Blunny's Well, Mullany's Well, and Lunny's Well. The saint himself is referred to variously as Mullana Naomhtha and Blunny Maruainigh, and the compilers noted that his name does not correspond to any entry in the Irish Calendar. The closest match they could find was Mlubhnáin Liaigh, whose feast fell on the 29th of March.

The well sits immediately north of Tullabracky Castle, with the ruins of Tullabracky church and its graveyard about 180 metres further north. According to local tradition recorded in 1840, the saint was believed to have founded the church at Tullabracky, referred to by some as a friary. A separate source, White's List as cited in Lenihan's history of Limerick, names the parish church of Tullabracky as a prebend, a church whose revenues supported a cathedral clergyman, and associates it with St Molan on the 5th of May. Whether this is the same figure under yet another corrupted name is unclear and remains unresolved. What is certain is that a pattern was once held here, a pattern being the traditional annual gathering at a holy well or church on a saint's feast day, involving prayer, circumambulation of the site, and often communal celebration. By 1840 the memory of which day it had fallen on was already lost.

By the time Caoimhín Ó Danachair documented the site in 1955, the spring had been enclosed and the water pumped away for domestic use. The devotional life of the well had effectively ended, though local people still maintained that the water could cure ailments. The well does not appear to be named on any map, which makes locating it a matter of knowing where to look rather than following signage. The cluster of sites in this part of Limerick, the castle, the church ruin, and the graveyard, provides the practical landmarks. The knee-print stone, if it survives intact, remains the most quietly odd thing about the place: a piece of rock held for generations to carry the physical impression of a saint whose name nobody could quite agree on.