Did my snail abandon his shell? What is this?

[JPG Corals]

So I just noticed this slug looking thing on my overflow. The shell I showed in my pictures, I though died...is this him out of his shell? Or something else? Because I saw his "trap door" in the sand...

 

[Tamberav]

The slug looking thing is a stomella snail. It is a good guy. Not related to your empty shell.

The stomella has a shell, it is just kind of a flat disc that covers it.

 

[JPG Corals]

The slug looking thing is a stomella snail. It is a good guy. Not related to your empty shell.

The stomella has a shell, it is just kind of a flat disc that covers it.

Well then, that is great. Thanks for the quick response!