The xenia wont sting.. but the mushroom may.
Depending on what kinda mushroom it is you can remove it different ways.. certain mushrooms you can actually take your fingernail and scrape close to the rock and it'll pry the entire mushroom as a whole off the rock.. which makes them easy to reattach wherever you want. Mushrooms like ricordea are a prime example of these easy-to-move mushrooms.
I've found that the more 'flimsy' type mushrooms are almost impossible to keep fully in tact while attempting to move it. Your best bet is to take a razor, place it on the rock by the shroom and scrape the mushroom completely off this way (scraping the rock at the base of the mushroom). This may rip the base of the mushroom a bit but it should grow back in no time. To attach to another rock take the mushroom and place it on a rock, then place a piece of net over top (do not do it tightly at all) then take a rubberband and secure the net onto the rock.