Somewhere in the old burial ground of Killeen Cormac, near Colbinstown in County Kildare, there lies, or once lay, a slab of green stone carved with an early ringed cross. The problem is that nobody has been able to find it.

The slab was recorded by Fitzgerald sometime between 1899 and 1902, described in enough detail to make it vivid: a flat green flagstone roughly five feet long and just over two feet across at its widest point, bearing a cross in relief, the arms joined by a ring or circle of the kind associated with early medieval Irish stone carving. Fitzgerald noted that the workmanship was, in his words, "very rude", meaning roughly executed rather than offensive, a common descriptor in antiquarian writing for carvings that lack fine finish. The cross itself measured about sixteen and a half inches along each axis. It was one of at least two such cross slabs recorded in the same burial ground, which adds a further layer of uncertainty: even the question of which slab the description refers to remains unresolved. Since Fitzgerald's time, the slab has not been relocated, leaving open the question of whether it was moved, buried beneath accumulated ground, or simply missed on subsequent visits.