Snail lost his shell?

Has anyone had an experience with a snail losing it's shell? I'll try to post a pic when I see it again. Is it something else? I have 2 of these that I have seen.

 

I just transfered my 55 to a nano and in the process of moving sand with my hands I sifted through and found a slug-like-snail with no shell. It freaked me because it was slimy and squishy. I put it in a holding cup aside from the tank and the thing fully disintegrated. I wish i would have taken photos...

 

Yeah, I've had that too. Only saw him once, so somebody made a snack o' him methinks.

 

I only have a sailfin and kole tang in the tank. I wish I had something that would kind of control them, but my goal is to have corals in my tank, so I don't know what to do.

 

I have heard of this before when the snail is dying from copper poisoning. I don't know if this is your case, but you might want to check it out.

 

Are you sure that you aren't seeing a stomatella snail?