In 1951, researchers found a mound roughly 20 metres long, oriented east to west, with about a dozen stones still protruding from it, many apparently undisturbed since they were first placed there. Twelve years later, when they returned, it was gone. The stones had been dragged from the mound and left in a pile against a nearby fence.

The monument had appeared on the 1913 edition of the Ordnance Survey six-inch map, which means it was still a visible and mappable feature at that point, whatever condition it was already in. When archaeologist Seán Ó Nualláin documented it for his 1989 Survey of the Megalithic Tombs of Ireland, he was working partly from that map record and partly from notes taken during the 1951 visit. What the earlier investigators had observed was suggestive: two of the eastern stones appeared to form a pair of jambs, the upright stones that would have flanked an entrance or forecourt. This detail, combined with the mound's considerable length, pointed towards the possibility of a court-tomb, a Neolithic monument type common in the north and west of Ireland, typically characterised by an open ceremonial court at one end leading into a roofed burial gallery. Without more of the structure surviving, though, Ó Nualláin could only flag the likelihood; the site was left formally unclassified.

The location itself, flat pasture land about 2.5 kilometres north-west of Skreen, with rock outcrops visible to the south, is the kind of modest agricultural ground where prehistoric monuments can be quietly absorbed into the working landscape over generations. There is nothing to see there now. What makes Carrownacreevy notable is precisely that absence, and the narrow window between 1951 and 1963 in which its disappearance was actually witnessed and recorded.