ID please?

[___]

Can anyone tell what's on my snail's shell please? Good? Bad?

 

[ying yang]

Maybe little tube worm.
If it got like a feather duster in it and you go near it and it retracts its that.
I had some on my hermits

 

[vetteguy53081]

Looks like a hydroid. Regardless of what you see, take shell out and place in small container of tank water and scrub/scrape it off