What are these????

[NanoReefer16]

I need help identifying what these little critters are?!! They look like small snails with no shells! I'm not sure if they're harmful or not and if they really are just snails? When the lights go out at night they cover the glass. Also, if they're harmful what can I do to erraticate them? Thanks for any help!

Sorry the first few pics aren't very good but keep scrolling until you hit the better ones.

 

[nemo1017]

Look like stomatellas to me. They're good.

 

[Tahoe61]

Look like stomatellas to me. They're good.

Yup

 

[Fish Werx]

+1 for Stomatellas.... Very useful to have, they seem to love film algae. I used to have tons of them, then my Melanurus Wrasse decided they were tasty... Now none....