Critter ID

[Jubo]

Saw a what looks to be some sort of a worm in my tank and I need a positive ID, it's about 3/4" long and moves pretty quick.

TIA

 

[Jubo]

Saw a what looks to be some sort of a worm in my tank and I need a positive ID, it's about 3/4" long and moves pretty quick.

TIA

Edit: I've found a few more of these worms, they are crawling out of the sand and up the back wall which I stopped cleaning a couple months ago, presumably eating algea, I think they might be Dorvilleidae worms.