It measures roughly 1.4 metres in length and rises no more than 0.65 metres from the ground, unremarkable to most eyes. Locally, though, it has long been known as a mass-rock, and that name carries considerable weight.

Mass-rocks are closely associated with the Penal Laws, the body of legislation enacted in Ireland from the late seventeenth century onwards that severely restricted Catholic worship, among other civil and religious freedoms. With church buildings banned or inaccessible, priests celebrated Mass outdoors at improvised altars, often flat-topped rocks in remote or sheltered spots, sometimes with a lookout posted nearby. This boulder at Clooncommon More sits just beyond the fosse, or defensive ditch, of a rath, the type of circular earthen enclosure commonly built in early medieval Ireland as a farmstead or homestead. The proximity of the mass-rock to that older boundary is unlikely to be accidental; such enclosures, already set apart from ordinary farmland, may have lent the spot a sense of occasion or offered a degree of natural concealment.