"we are talking stoneage"

I see what you are talking about...

The rock does seem to have some kind of a sculpture of man on it... that does seem to get enhanced by the show's graphics team...

However, I think we only see this because of "a bit of clever "photoshopping"". The production team just got really lucky in finding a rock that they were able to "morph" into a man.

There is a term that I have heard called "Matrixing". The human mind tries to look for patterns in chaos. Like seeing objects in clouds.

I myself saw what looked like a bottlenose dolphin in some clouds just a couple of days ago. Pretty Cool. But, I know it was just an illusion...

These things happen all the time.

There are also times, when you see something you can't identify, and then someone who is with you will say, it looks like a "Man" or "Dolphin". And then you see a "Man" or "Dolphin".

I think this is what happened in the episode. You see some weird rock shape, and then they place this image of a man over it, and then you see the man without the image.

But as I said, they did seem to get very lucky in finding this rock. So who knows...

However, if you look at the man, it looks like a half naked "Stoneage" man, not a Roman soldier. So this can't be proof that Merlin was involved.

Actually the image of the man looks like he has an afro to me. Weird.

It just so happens I saw that part of that episode recently too. It seemed to me that the only reason that graphic was shown on the screen at that moment was to show the likely crudeness of stoneage man (clothes, basic club as a weapon, etc) and how that wouldn't seem to fit with those who corroborate the idea he was sophisticated enough at the time to have built the types of precise structures that were being talked about during that part of the episode.