Hello Harry,
I'm not sure I understand your question about Napoleon fish. You said
"just name the shell"?? Is the "Napoleon fish" you are looking for a
shelled mollusk? There is a type of wrasse called Napoleon fish. If
that's what you are looking for, you can see it here:
http://www.animalpicturesarchive.com/animal/APAsrch3.cgi?qt=Napoleon%20fish
Paul M.