Are these hydroids?

[feeeesh]

I’m not sure what these are. They’re showing up in my tank. I have a fish only with live rock. Have not introduced anything new to my tank in over a year. Any thoughts on what it is and how I can get rid of them?

 

[Crabs McJones]

Not one i've seen before @ISpeakForTheSeas any idea?

 

[Texasreef]

Unfortunately that looks like Aiptasia

 

[ISpeakForTheSeas]

I’m not sure what these are. They’re showing up in my tank. I have a fish only with live rock. Have not introduced anything new to my tank in over a year. Any thoughts on what it is and how I can get rid of them?

I've seen one spaghetti worm that looks similar, but my first thought is that this is either an anemone or a similar critter.

OP, do these have one or two whorls of tentacles? (One whorl is like a normal anemone with tentacles around the outside; two whorls has that outer whorl and a whorl basically inside the mouth - two whorls are only found on tube anemones).