[mrshagzsf]

This little guy showed up in my new tank a few days ago. He opens and closed sometimes but is mostly wide open..

 

[archer772]

Looks like it could be a rock anemone

 

[FreeEnterprise]

yeah, looks like a rock anenome to me too.

 

[maryg]

Does it retract when you touch it? If it does it is bad. If it doesn't then you should be ok.