glass anenome, aptasia, curly cue, they are all the same and all bad for your tank. they spread quick and pack a pretty good sting. you will want to get rid of them as quick as possible. You can rid these a few ways. like wrasse said peppermint shrimp work good but tend to munch on other soft corals. Copperbanded butterfly fish works awesome. what I would recommend is getting some kalkawasser and mixing it into a paste and inject if onto them. that works awesome. but you will want to remedy this quickly