Dont know what these are

[Barbaracortez5669]

I have no idea what these are, are they safe?, they appeared out of nowhere, will they kill my clowns? They only come out when tank lights are off as soon as lights come on they retreat,

 

[sixty_reefer]

They ball anemone

 

[Cell]

I was thinking medusa hydroid.

 

[Scrubber_steve]

Ball anemone going by the hitchhiker thread

 

[reef lover]

Corynactis...ball nem