The Coflein record, to be fair, isn’t sure how old this stone is. It describes it as “an upright slab, 2.8m high by 1.7m by 0.5-0.8m” possibly on a mound.
I think it could well be the one mentioned here in on p186 of “Tales of the Cymry: with notes illustrative and explanatory” by James Motley (1848).
It is reported of a large stone near the end of the old canal, but on the left of the road from Neath to Brittonferry, that there is a charm, not yet discovered, which can compel it to speak, and for once to reveal the secret of its history: but that having once spoken it will be silent for ever.
Online at the Internet Archive.
