These are in my parents tank have no idea what they are. Looking to find out what they are and if they are a threat. The long tube one looks like a little feather duster but IDK for sure thank yal.
Basically, they're anemones. Most of them are small, but overtime they can multiply to the tens and twenties, grow to be a decent size, and if they go untreated, will take over a tank. They will sting nearby corals, irritating them and fish that come close.
I've killed them with peppermint shrimp and aipstasia X