It measures roughly 0.7 metres by 0.78 metres, and the cross cut into its face has a shaft of 0.38 metres and a span of 0.29 metres. Small, weathered, and easily overlooked in the mountain scrubland around it, this is what locals call a mass rock.

Mass rocks are among the more quietly charged survivals of Irish religious life under the Penal Laws, the series of statutes enacted in the late seventeenth and early eighteenth centuries that severely restricted Catholic worship. With churches closed or destroyed and priests subject to arrest, congregations moved their liturgy outdoors, gathering in remote or concealed spots where a flat stone could serve as an altar. The rock at Boleynanoultagh sits on the flank of Carrigeenamronety, known locally as Quern Hill, a name that suggests the hill had its own workaday significance long before or alongside its use for clandestine worship. The cross is carved in relief on the south face of the upright slab, oriented to catch whatever light the hillside allows, a simple mark that transformed an ordinary piece of local stone into a sacred object.