Featured Ivory? Cane top? Art Deco?

Picked this up for a buck at the thrift store. Best guess is that it is a cane top, though it doesn't fit the hand terribly well. Seems it should have more of a knob shape. Seems a bit large and heavy for a parasol handle. 4.5" long (11.5 cm.) long. Widest point is just slightly over 1.5" (4cm.). Looks like the top dome is a separate piece but I can't get it to unscrew. May try to clean it a bit and try again. What do you all say?

 

Schreger lines sure seem to be visible on your pics.

 

Definitely ivory. Traveling corkscrew missing a bit?

 

Thritto re ivory. The 'stone' looks like glass.
No idea what the item could be, but it doesn't look like a cane or parasol handle to me. Looks like we need Marote to find something similar, but he is away for a month, with little internet access.