I.D. please - Hard tubes

[GoFish]

little hard tubes all over this mushroom covered rock. They secrete some slime once in a while but i never see anything other than that come out
Whenever i move the rock i get poked by them, so wouldn't mind getting rid of them, if so i don't want them to spread if i scrape them off
Advice and ID?
Thanks in advance

[Acrowhora]

those are vermittid snails...they're harmless

[GoFish]

Perfect, thanks

[Myka]

If you have lots of them you should try to control the population by manual removal because the stringy feeding webs that they send out can irritate surrounding corals.