I'm absolutely no expert, so please feel free to read my comments with that in mind.
I have a toadstool leather which came attached to a small piece of rock, popped it into the tank and it seemd ok. Woke up the following morning to find it lying on the bottom of the tank.
LFS told me to 'wedge it between some rocks' ... I did so, it reattacched itself and is really beatiful now.