couple ways........in both methods I will describe you want to first seperate the polyps from the rest of the colony mat by cutting with a razor or scalpel or my preferred tool of choice is old fly tying scissors as I have a box full fo them and I can easily cut in between individual polyps by point the end of the scissors straight down in between them and snipping through the mat inot he rock......regardless, of how you do it........seperate all flesh in between the colony and what you want to frag off...
Then....
1. you can either chip, cut or shave rock out from underneath them which is the preferred method if its reasonable to do so as you can then very easily glue the polyps with the rock underneath then to some thing else with much less stress to the polyps than the next method
2. scrape or pull only the mat and polyps up. then glue where you want. When you do this try to use as little as glue as possible. If you end up with a huge wad of glue around the polyp creating a well it not only takes it longer to grow around it than if the mat could just start growing outward, it also creates a place in which crap can settle and if you dont have tons of flow or regularly blow them out this can allow them to get infected much easier than if that well didnt exist, especially before any wounds heal. you want open wounds clean