A bullaun (Irish: bullán; from a word cognate with "bowl" and French bol) is the term used for the depression in a stone which is often water filled. Natural rounded boulders or pebbles may sit in the bullaun. The size of the bullaun is highly variable and these hemispherical cups hollowed out of a rock may come as singles or multiples with the same rock. Local folklore often attaches religious or magical significance to bullaun stones, such as the belief that the rainwater collecting in a stone's hollow has healing properties.
https://en.wikipedia.org/wiki/Bullaun
A bullaun (Irish: bullán; from a word cognate with "bowl" and French bol) is the term used for the depression in a stone which is often water filled. Natural rounded boulders or pebbles may sit in the bullaun. The size of the bullaun is highly variable and these hemispherical cups hollowed out of a rock may come as singles or multiples with the same rock. Local folklore often attaches religious or magical significance to bullaun stones, such as the belief that the rainwater collecting in a stone's hollow has healing properties.
