Slug ID, Please

[JackTheReefer]

Found a new creature tonight in my son's 55 gal reef tank. Been a year or so since any new live rock was introduced. This thing does not like the light, and was retreating as soon as we turned on the lights.

Looks like I've successfully attached the photos.

 

[LeslieH]

Just your typical Stomatella snail searching for some tasty micro-algae to eat.

 

[JackTheReefer]

So that purple spot is it's shell?

 

[Elysia]

Their shells are often described as "finger nail like." Often a lot of the snail's foot is exposed at the rear of the shell.

 

[JackTheReefer]

Are they asexual? I'm thinking there is only one, but maybe there are more.