Exceptional indeed. I'll never forget the day I first saw that. The problem with Reyfad is that it has been moved and obviously with some force, so it's hard to tell how significant the fissures were when the carving was done. The large one has almost certainly opened up. After looking at many photos of it I can't see a fissure directly incorporated into a motif. The only drawing I have is from the 19th C and doesn't include the fissures.