These depressions are not decorative and were not made by tools. According to local tradition, they are the imprints left by the knees of a fugitive who stopped at the well to drink, pressing down long enough, or with enough desperation, to leave a permanent mark in the stone. It is the kind of story that attaches itself to old stones and old water sources throughout Ireland, and it is no less interesting for that.

The stone is a bullaun, a type found at early Christian and pre-Christian sites across Ireland. Bullauns are stones, usually glacial boulders or worked slabs, bearing one or more rounded, cup-like hollows, and they appear frequently near holy wells, churches, and monastic enclosures. Their original purpose is not agreed upon; suggestions range from liturgical use to grain-grinding to ritual. The Killowen example, recorded by Ó Riordáin in 1932, sits on the southern side of the associated holy well. It is a modest piece of stone, measuring roughly 86 centimetres by 57 centimetres and standing only 15 centimetres high. The two hollows at its northern end differ slightly in size, one around 18 centimetres across and 6 centimetres deep, the other 23 centimetres wide and 10 centimetres deep. That asymmetry, and the folklore explanation of kneeling rather than grinding or ritual use, gives this particular bullaun a character of its own.