What is this growth in my aquarium?

[Lillyrosesmum]

It started growing not too long ago. There are tubes with tiny creatures inside. What could it be?

 

[JMMJ13902]

Some kind of worms, they spit out some kinds of nest (looks like spider webb) and pull them in to eat. I hear they will harm your corals so I used the plier to take them off the rock.

 

[Reefing Madness]

VERMITID SNAILS
Snails That Worm Their Way Into Tanks by Ronald L. Shimek, Ph.D. - Reefkeeping.com