[gerdesj]

"The boulder with the markings is 3.5 to 4 feet high and about 5 feet long. Photos show a surface with numerous fissures."

A very strong bored kid.

At the bottom of my garden there was the concrete remains of some bridge footings. There's a stream at the perimeter and Dr Beeching caused the bridge to be no longer needed back in the day. Anyway, I dug them out and the largest was a lump about 4'x3'x2'. It nearly killed ... it took a lot of effort and some funky lever action with a very long modern steel crowbar to move and the rest had some quality time with my hammer drill and a SDS chisel bit and the mechanism set to hammer with no spin (obvs).

Anyway, enough of the foundations of my rockery.

Autism? Not indicated. You are looking for Godzilla or King Kong.