It has a small shell and even a little head that sticks out with antennas, moves pretty fast too (for a snail). I did a look up on stomatella and it looks exactly like that, except for the colors. This one is more green. But I have others in the tank, just like it with different colors, some brown, some black with white dots.
I do have these other things in the tank... white, look like little snails but without the shell, sort of split where the head is, kinda like slugs. They're really tiny and usually come out at night, on the glass.
