Hi, I have no idea where that one came from, it's a very nice shell.... but I do know where you can get a shell similar to that... here's the link:

http://www.most-digital-creations.com/free_poser_poses_textures_morphs_props_34.htm

Just scroll down and it should be the 3rd or 4th freebie on that page.... AdamThwaits is a great vendor so I usually get stuff from him.

Hope this helps, sorry I couldn't find the shell you wanted. :D