What is this? Live rock hitchhiker I think

[t to the maxx2]

What is this? I just was lookin at the tank and saw it cruisin the wall? Is it good? Bad? What should I do?
Last rock I got was 2 weeks ago.

 

[Bebo77]

dont know... maybe a bristlel worm? i would take it out.... but this link may help you

http://www.reefs.org/hhfaq/pages/main_pages/faq_rock3.htm

 

[cilyjr]

could be a small bristol worm.

 

[LeslieH]

It's the epitoke stage of a polychaete worm in the family Nereididae. Epitokes are sexually mature reproductive morphs which carry eggs & sperm up into the water column where they spawn. Some types of epitokes - including the one in your picture - have become nothing more than sacs of skin with big eyes & bristles which burst open to release the gametes. Nothing to worry about.