Wow - what cut that rock?

In the Roller Coaster tunnel there is a piece of ROCK that ran along the floor that looks like the top edge of it has been cleanly sliced off for about a foot or more along it's length.

I mean beyond the carelessness and needless damage to the cave didn't that #### up somebody's scooter shroud? If it was a scooter was it a metal or a plastic shroud? and what was the damage to the sccoter if any?

Or maybe it wasn't even a scooter - I'm still trying to understand what could have caused that damage, what happened and whether it was done on the way in or the way OUT of the cave (since there are bits of rock 20' farther out along the passage that might be part of some other accident or maybe just part of the same thing.)

I don't want to know who did it but how about a nice detailed IRAP on that one?