Star fish or worm? Bad or good?

[reynaldoramon]

Saw this tiny guy on my glass these evening. Took a few pictures. From the side and behind.

Would initially guess some kind of star fish, but looks like appendages have antenna on them. Thoughts? Recommendations?

 

[JedClampett]

Astera starfish, they are fine but can multiply.

 

[iretthepirate]

Kill that mother. Multiply like weeds some people say they will eat coral. They over took my tank had to get harlequins to fix