Plate corals (Fungio, heliofungia) apparently inflate and deflate themselves to move around. therefore, like mystikdragon7 said, put it in the sand where it won't hurt itself. Gluing it to a rock would be a mistake and it would hurt itself.
As an interesting note, my reef club (BAR) had a fragging workshop where we cut up a helio fungia (brutally!) with a chisel. I couldn't believe anything could survive that as it looked like pieces of dead coral skeleton right after the fragging. 6 months or so later, I now have two healthy helio fungias! I'm always amazed how resiliant corals are!
They don't move, but their tentacles inflate and deflate.
Have fun!
V