Mystery Object

We at the Field Museum are excitedly planning for our fall exhibiton, Opening the Vaults: World's Fair.  In their planning, our exhibiton team came accross a mystery idem that they can't identify.  Matt Matcuk posted about it on his blog.  I love a good mystery, and it would be great if we could solve this one together.  Let us know if you have any ideas about what this might be.