What are these ??? Are they harmless ? Or will they hurt my corals they sure look like crap and make my corals not look the best and clean. Can I simply pull them off?
These look like aptasia to me. Aptasia are pest anemones and yes they can sting corals. They are almost impossible to keep out of your tank but there are a handful of ways to keep the numbers down. My favorite way is getting berghia nudibranchs to feed on them as long you don’t have fish that would prey on the nudibranchs
Looks like aiptasia. Hitchhiker, they do bother corals. There are many ways of getting rid of them. Natural and unnatural way. Peppermint shrimp or aiptasia eating file fish works great too.
Also a side note, irritating them will cause them to release babies so I don’t recommend trying to pull them off or anything like that. I learned this the hard way and I ended up with 10 times the amount within a few weeks. There’s are ways to kill them besides using fish or inverts with stuff you can buy, most notably aptasia x or F-aptasia but this way can be a bit messy. I would recommend watching some videos on how to do it if you chose that route though. Hope this helps!