It is, or was, a large limestone boulder, one that served as an improvised altar during the Penal Laws, the period from the late seventeenth into the eighteenth century when Catholic worship was effectively outlawed in Ireland and Mass was said in secret, often outdoors and in remote locations. The boulder at Carrick became known as the Cross of Carrick, a name that persisted on the Ordnance Survey Fair Plan, giving it a cartographic dignity that outlasted whatever physical presence it once had.

By the time the Ordnance Survey Field Name Books recorded details about the site in 1837, the spot was already slipping into obscurity. The entry noted that the cross marked where a Catholic altar had formerly stood, adding that "the track of which at present is scarcely to be observed." The boulder sat within, or near the centre of, a reilig na páistí, an Irish term for a children's burial ground, sometimes called a cillin, where infants who died unbaptised were interred in unconsecrated ground, apart from the main parish cemetery. That enclosure adjoined the cross site and was itself destroyed at some point; by the time the site was surveyed in 1980, no burials had taken place there since around the turn of the twentieth century, and the landowner's account was the primary source of information about what the boulder had once signified. A few large boulders remained along a nearby field fence, though surveyors noted these appeared to carry no archaeological significance, quiet remnants of a place whose meaning had largely dissolved into local memory.