What made it notable was not its size, just under a metre in height, but three close-set hollows worn or worked into its surface, said to resemble the paw print of a dog. Stones with cupmarks, shallow circular depressions thought to date from the Bronze Age or earlier, are found across Ireland, but an impression interpreted as an animal print is an unusual detail, the kind of thing that tends to lodge in local memory and generate its own folklore.

Leinster archaeologist Liam Price recorded the stone in 1934, noting its modest dimensions and its prominent hilltop position. Knockdoo itself, the name likely deriving from the Irish for black hill, is described as a gravel hillock with steep sides, the sort of natural feature that prehistoric communities often chose for monuments, whether as a marker visible across the landscape or a place already considered significant. Sometime during the 1980s, the stone was removed, not by the landowner but by person or persons unknown. It has not been recovered, and the hollow at the summit where it stood is all that remains of whatever purpose it once served.