I've been looking this up for something else, and this information doesn't add to the thread but explains my question regarding the shell being a salt further up the thread.
I still feel these glass nautilus shells were created as salts

These are a pair of silver nautilus shell salts with their original spoons in their original box c. 1850
http://www.spencermarks.com/items/h211.htmland this is a wiki explanation of how salts were used at the table
http://en.wikipedia.org/wiki/Salt_spoonm