It's a slug but good or bad?

[Yuki Rihwa]

I found another intruder! Yeah, this hobby really amazed me with all kind of unexpected critter showing up from time to time

another picture

I just don't know this one is a good slug or bad slug though, any suggestions or its ID are welcome and thanks in advance!

 

[aKlevans]

Stomatella snail, good.

 

[Lovemyreef2015]

Looks like a stomatella snail

 

[Yuki Rihwa]

Thank you all, back to the tank it is