well i succeded with a hard exacto and now i have 4 colonies. Take the most separated specimen of the group, cut it clean where the flesh is thin..well cut the "foot" ( yellow lines ) and if it's detached, try to cut/scrape the rock under the polyp ( red lines ) so you will not hurt the animal. Then you could put the specimen on a hollowed rock or rubble in an area when there is no flow, but light. Even if the polyp in on his side, he'll stick eventually to the rock then move toward the light. If you have too much flow, you could hang a 1 $ drilled basket in your tank, near the waterline...filled with rubbles, the polyp will be happy.