I gve it 8. I really love the soft look and the shades of white - and the composition. I absolutely agree with the comment by Melethia: I love the way it interacts with the background. it does not look like any common smooth shell photos which is a huge plus for me!
I, too, like how it fades into the background. This isn't always a plus on DPC, but to me it does work on some photos - this is one of them. I do have agree that the subject of the photo (a shell) appeared a whole lot in this challenge and may have overwhelmed voters a bit. I also agree with Jeff that this would make a very nice notecard.
There's a sort of genre to white (pale) on white photographs, in which the foreground object needs to be sharp and the background needs to be clean. (My entry doesn't comply with any of this, NB). This gets very close to it. I'd agree with a few comments that would have the shell a bit sharper, etc, etc, but the subject and composition are really good. I gave it 7.
I gave this a 6, which was pretty high in this challenge. It has lovely curves and I like how it blends into the white (but that blending probably cost you with other voters). I didn't vote it higher because I'm shell-shocked. :) I see so many of these shell photos, but yours is one of the better ones. Your composition isn't bad, but it doesn't add interest, either.