the easiest way is to break a chunk of the rock off. or you can peel back a section of the mat (the purple undergrowth) lift the edge of it with a butter knife and slowly scrape/pull back peeling off as big a piecs as you want, it tends to break easy so it may take a bunch of small pieces to get as much as you want, then dry the rock you want to glue it to with paper towel, and dry the back of the star polyp too. put super glue gel on the rock where you want the polyp to be and gently press it into the glue once your piece/pieces are attached give it 30 seconds to a minute to dry, then place back in the tank. (I reccomend wearing rubber gloves while doing this so you dont accidently glue your finger to the rock while pressing in frags. Ive done it, its no fun)