A small and rather uninspiring stone hidden behind a dry stone wall right next to the A4080 running south from the A5 towards Barclodiad y Gawres. Interesting for the Roman (?) inscriptions carved on to it.
This is a Dark Age christian memorial stone from around the 6th century CE. The RCAHMW gives the inscription as 'CUNOGUSI HIC IACIT' [Latin for 'Cunogusus lies here']. The letters are still fairly easy to make out.
There is a rumour that the stone has a cup mark on one side, making it a re-used prehistoric menhir, but I couldn't find it.
Apparently the name Cunogusus is preserved in the name of the nearest village, Pencarnisiog, which if true would be a wonderful example of continuity over the last twelve centuries.
I've had a peek at CARN, and this stone is listed as Medieval by Gwynedd Archaeological Trust, Cadw and RCAHMW. I've not looked at the records themselves, so there may be some ambiguity about the age of the stone that isn't identifiable from the catalogue.