I've got a really awesome green and blue mushroom, but its placed itself in the very back of the rock work. Is there anything I can do? I cannot move the rocks.
You could try to point a power head at it and see if that will make it move. If not, I would just leave it. Trying to pry it out of the rock might harm it.
The videos I've seen of people removing/fragging them all involve completely removing the rock and basically using a chisel to gouge out a chunk of rock under the mushroom to remove it without harm. My blue/green splits pretty frequently as well. Maybe glue some bits of rubble rock to the base rock he's on (almost under him really) so when he splits, it's very likely one half will anchor to a little piece you can easily move.