Strange snail... maybe an Abalone?
 

So, back when I added the Calgary livestock to my tank, I found a tiny snail in one of the acclimation vessels. He didn't seem to be doing too well (snails need to be drip acclimated, I understand), but I tossed him in the tank anyway (his shell was probably 3/8" long). He has interesting iridescent colors in his shell, so I thought I'd give him a chance. Well, that was a month ago, and yesterday an hour or so before lights out, I see this greenish colored thing crawling across one of the rocks!

He's in the hollow in the middle of the pic...
http://i633.photobucket.com/albums/u...20reef/053.jpg

Any ideas as to what he is? His shell doesn't look spiraled or whorled like a normal snail, and he's a little small to really identify him properly (I put him back in and probably won't see him again for a while). He's also at least doubled in size in a month.

Probably a stomatella snail.

+1 stomatella 100%. Good critter to have.

Cool, I was under the impression that Stomatella's are pretty small so I figured it was something else. Thanks for the help, much appreciated!

I've seen Stomatellas up to 1" long so they can reach a pretty good size.

Good to know, this guy is quickly reaching that point.