Tobar na Péiste translates roughly as the Well of the Worm, or more precisely the well of the péist, the serpentine monster of Irish folklore, and the name attached not just to the water source but to the townland around it. The curative tradition recorded in the Ordnance Survey Letters of 1839 was specific and practical: people came here to wash their hands as a remedy against worm, a term that once covered a range of ailments associated with parasitic or creeping afflictions.

The well carries two overlapping stories, one medical and one hagiographic. The older-seeming layer is the folk remedy, the simple act of washing in water believed to have particular properties against worms. The other layer, recorded by the historian William Carrigan in 1905, gives the well a more dramatic origin. A saint, whose name had already been lost by Carrigan's time, was said to have fought and killed the péist at this spot. Exhausted and thirsty after the struggle, he was refreshed by a spring that burst forth miraculously from the ground. It is a familiar structure in Irish sacred geography, where holy wells frequently mark the site of a saint's exertion or encounter with some hostile force. The well sits in a broad, flat river valley, roughly sixty metres north of the Nuenna River, a quiet and unremarkable setting that gives little away.

The well is no longer venerated, and a concrete covering now marks the site, positioned a little south of where the older Ordnance Survey maps place it. The gap between the mapped location and the current cover is modest, around ten metres, but it is a small reminder of how these sites shift, are altered, or quietly fall out of use while the name that carries their history lingers on in the landscape.