Coral frag plugs aren’t the easiest things to mount to your live rock. The odd shape of the plug doesn’t fit right anywhere, and who wants to see a very artificial structure in a tank full of natural, living things. Most of the time, it’s more aesthetically pleasing to just remove the coral from the plug and glue it straight onto the rock. The leftover frag plug isn’t trash though. It can be reused over and over again along with many other reef aquarium related items. Just scrape off any glue from the frag plug and you can glue onto it any frags you make.