Wierd Stringy things

[Renegade]

Hey guys this is kinda a newbe question but in almost 2 yrs i've never encountered this before. First off i don't have any pictures b/c it would just be blurry so i'm not going to ask to take a look at a picture and try and identify something.

Ok so i have a 20g set up that has about 35pounds of LR in it. Its temporary as i was curing rock temporary has turned into 6months now lol. it has crabs and snails in it. So my question is i have these wierd string thing about the diamator of a hair (white) with little feelers on it. They retract but for the most part are out 24/7, some kind of worm perhaps ?

If so good / bad and if bad how do i get rid of them ?

I know this is incredibly vage but iono how else to discribe it.

Thanks

Kyle