Creepy worm pest ID please!

[Benga]

I've been noticing on the top of my sand bed these weird green tentacles but they almost looked like detritus or algae but then i decided to get my tweezers and see if i could grab a clump and then I noticed it actually looks like a worm. I found two of these but am fairly certain i have a whole ton more.

They creep me the heck out!! But if they're good for the reef I'll let them survive.

 

[Gtinnel]

I believe they're spaghetti worms, and if I'm right they're a good worms.

 

[Coral therapy]

They are spaghetti worms, ive never had any issues with them. they seem more beneficial than not.

 

[Benga]

I believe they're spaghetti worms, and if I'm right they're a good worms.

They are spaghetti worms, ive never had any issues with them. they seem more beneficial than not.

Solid thank you both, looks like that's the critter. Back in the tank it goes...