Can anybody ID this possible pest?

[MangoSentinels]

Hey Reefers,

I've noticed this stringy thing starting to grow on my rocks and sandbed but am not sure what it is, if its harmful and how to keep it under control. Any input would be greatly appreciated.

 

[tjohnson3]

Really hard to tell from pic, but looks like possible spaghetti worm… those are safe

 

[T-J]

Spaghetti worm. Good part of CUC.

 

[BanjoBandito]