Weird worms

[J_____P]

Saw these small white worms in the live rock I purchased. This is my first tank, the rock was not dipped after picking it up from my LFS. Just wondering if this is a pest or something that is not harmful. There are no fish or coral in the tank and has been cycling for 3 days now. Should I be worried!?

 

[Mushroomsyo]

Looks like a spaghetti worm. Keep it, they are good cuc.

 

[Sean Clark]

@Erin1971Texas help please.

 

[EeyoreIsMySpiritAnimal]

Saw these small white worms in the live rock I purchased. This is my first tank, the rock was not dipped after picking it up from my LFS. Just wondering if this is a pest or something that is not harmful. There are no fish or coral in the tank and has been cycling for 3 days now. Should I be worried!?

Have you asked your LFS?
Looks like tentacles from a spaghetti worm or other detritivore.
Since you're new to reefing (welcome!), check out some of the sticky threads on this forum to learn about common hitchhikers.