Sea Slug? Anyone know what kind?

[talloulou]

I got up very early this morning and found another hitchiker in my tank! It looks like a sea slug although there is a dark circle looking thing on it's back which looks hard....maybe? Is it a sea slug? Any idea what kind? At first I thought one of my two turbo snails lost a shell but they are both accounted for Here are pics of front and back.

 

[talloulou]

...ooops sorry! Here is the other side.

 

[Fluff]

It's a type of snail called Stomatella varia. Great algae grazers and will reproduce in your tank.

 

[talloulou]

Thanks fluff!