1. Cutting around each polyp with a SHARP razor blade.
This method is very easy if there is no base rock, or the base the zoanthids are on is soft. I don’t recommend scraping them off but rather attempting to get the razor blade under the zoanthids as well as a thin layer of rock. I also do not recommend just cutting them in half, but know individuals who have had great success doing so.
2. Chisel off the pieces you want.
Using a chisel works great if the zoanthids are on a thick base rock that is very solid rather than soft. It allows you to just bust pieces off the base rock rather than trying to dig under solid rock.
3. Dremel them off the rock.
This can be tricky, but with a diamond blade dremel, you can cut under the zoanthids base rock. Once you cut about a quarter of an inch under the rock, you can take a flathead screwdriver and place it in the slit cut by the dremel and twist. The frag made, will usually just pop right off. You may need a razor blade to cut the frag from the mother colony.
Frags are great because it allows you to get more color combinations, since there are so many different colors, patterns, and morphs.