Hello,
You can also put some small pieces of reef rubble on top or touching them. They usually attach to the rubble in a few days or weeks. They then can be glued to a location of your preference.
I collect loose mushrooms and place them in the bottom of a small plastic container then place reef rubble on top of them. As they climb up to get light they naturally attach to the rubble. The container prevents them from being blown around and keeps the rubble from spreading out. The rubble I use is about the size of a grape. They tend to attach more quickly using this method.
Cheers,
Kevin