These plugs work wonderfully. Ive used them for attaching loose mushrooms after they attach to a piece of crushed coral. Simply glue, attach and place in the tank. I highly recommend these especially for the price.

Somewhat pricey compared to other options, but, better than competitors large discs that do not have a pin on them to keep them in eggcrate. I use these primarily for zoanthid and LPS frag growout, but I am sure they would work well for SPS frags too, and would give a nice broad base for the SPS to encrust to.