mystery critter

[kilkman]

some sort of sea cucumber or slug riding around on turbo snail spreading what looks like webbing all over the place. any clue as to what it is?

 

[KrisReef]

Take that snail out and scrape off the vermitid tube snail that is hitchhiking on the snail shell. These can spread around your tank and irritate corals ime.

 

[WheatToast]

Very large Vermetid snail. These can produce mucus that irritates corals and multiply rapidly.
Usually, it is recommended to cover the snail with glue or crush the base of the shell with tweezers.
@vetteguy53081