A baby in my tank?

[Marinebeginner]

Something has bred in my tank .... Turned lights off and discovered a small mollusc climbing up the glass. About 5-7mm in size. I have turbo snails, one conch who has been lonesome for 3-4 months and also recent addition of a sea hare. I'm guessing either sea hare was pregnant when I got it (?) or turbos have bred but it doesn't appear to have shell. When do they develop shells? Tried to take photo but pretty crap.
Also I bought a new coral a few weeks ago so maybe a totally new inhabitant?
Any suggestions ? Ta!!

 

[Nu-Nu the eel]

Stomatella snail. Just a regular old hitch hiker.

 

[Marinebeginner]

Aha! Googled images and yes that's exactly what it looks like. Thanks. That's a relief- don't have enough algae for another sea hare!
Good value for money with my last coral then I guess...?

 

[Nu-Nu the eel]

Lol well they pretty much end up in every tank... Quite common. Kinda cool i guess

 

[Ericwm]

I got 2 as hitch hikers, is there any chance they mite reproduce? They both look a bit different.

 

[Nu-Nu the eel]

Yes they certainly could