Sorry for the blue photo but hopefully it won’t matter. I have a couple frags of black sun coral. They have been doing good for a month or so. A few days ago I noticed dark brown spots. Tried to suck one up with Baster. Nothing. They did shrink a little. Worried they were maybe flat worms. Pulled the frag and dipped in coral rx. They didn’t move only shrank a little. Put back in the tank. Today dipped again. Same thing. I tried to scrape one off and it seems like they are in or really attached. See none on the other frags around the tank. They aren’t on the tissue. Only the coral shaft. Any ideas?