Funny looking hitch hiker (Can you ID him)

[Delphinus]

If it looks like a miniature abalone, then my guess is it's a Stomatella sp. snail, which comes in sometimes on rock from Indonesia and vicinity. Awesome little algae grazers, and will multiply in our reef tanks. Do a search on "stomatella" maybe and see if this is what you have. Alternative, I know that TRA Vol I or II has a picture of these guys, check the index if you can get your hands on those books.

The "turtle" shell kind of makes me wonder if it could be something else though... sure you can't get a picture of it? The ones I have in my tank, I wouldn't describe their shell as like a turtle's. More like a small fingernail. I can't see how this shell could possibly shelter these snails, it's way too small for them.