Pest or Beneficial?

[nitro500]

Did a water change last night and this guy got sucked up. Never seen before but noticed the same stringy 'legs' in other parts of the tank. It has a worm body and lots of legs...

Any idea what this is? Helpful for the tank or something from the Upside Down?

 

[WheatToast]

Spaghetti/hair worm, a beneficial detritivore.

 

[MaxTremors]

Beneficial detritivore that helps keep sand/rock clean.

 

[nitro500]

WHEW! Thank you!!

 

[WWC]

Very Beneficial and cool little guys to have!