here is an article that talks about attaching corals using a variety of methods, its very handy
http://www.garf.org/news25p2.html
, but as ive heard, silicone is a good glue to use on coral because it is very unreactive element and will not react with the water or the coral. but tommys right, its not the best method because it takes much longer to harden underwater and requires a lot of holding your coral in place underwater. It might save you allot of time if you just can rubber band it on. Ive olso seen you can use a paper clip to wrap around the base of your coral and push the other end into a hole in the rock in a way that the base of the coral is touching the rock, I dont know if paper clips are bad for the tank though,
