Any clue what this is?

[mustnggt619]

i have this worm thing in my new tank and trying to figure out what it is.
It doesnt like light and shrinks as soon as it has strong light on it.
View attachment 3934 Any help would be appritiated

 

[Wicked Color]

polychaete worm, commonly called elephant worm, can be a nuisance.

 

[cindys]

Is that the same as a peanut worm? What is a nuisance about it?