credit goes to bro Roger, i only attached abt 3 polyps of my own collection onto it.. anyway, there's a few ways to doing this, u could chip off the mushroom with abit of rock, and superglue the tiny rock piece onto the multicolour rock that u want.. wait a few days for it to stabilise and hopefully it will spread its roots across onto the main rock..
another way, if u have loose frags of mushrooms (without base), i use rubber band to loosely band down the mushroom onto the rock, and put it in my refugium and in a matter of days it should naturally stick onto the rock already.. hope that helps..