Weird starfish looking thing on zoa frag

[gabedickerson7]

Hi I just picked up a new zoa frag from world wide corals and there seems to be a starfish looking thing crawling around with tentacles somewhat like bristle worms. Don’t know if I should leave it or kill it before it goes into my tank also would like to know what it is is anyone has any insight.

 

[Fishy212]

looks like a serpent star or brittle star

 

[gabedickerson7]

looks like a serpent star or brittle star

Are either of them harmful to any of my corals and fish?

 

[Fishy212]

beneficial CUC members. No need to worry about them.