Bone? Buttons

OK, not a textile person at all, but I was at a garage sale and thought these were kinda neat. Bone? Antler? I think shellacked or something for a shiny surface. Handmade? Also came with a cool bone ring, but dang! doesn't fit any of my fingers. Any idea of what vintage they might be? I'm think they're off a

 

Don't know about age, but one possibility might be that these are opercula (not the ones used by NW Coast natives though).
That is, the little trapdoors made and used by ocean snails to close their shells.
https://en.wikipedia.org/wiki/Operculum_(gastropod)

 

geez...i can't tell what those are ?

 

Opercula are often sold to the beading/jewelry trade as "Cat's eye shells."
Compare http://www.ebay.com/itm/CATS-EYE-OPERCULUM-TURBINIDAE-VINTAGE-/132296344181
or





Any evidence of a spiral on the back?

 

I wish they we're opercula. The second row shows the button underside -- the shank to sew on the button. You can see holes in the material which to me means bone. They are also lightweight. I was wondering if someone sliced an antler or such and carved/grinded and smoothed into button shapes. What, though, would have the dark middle, white ring and then outer grey ring?

 

Looks like some type of antler to me,the shape is right and the porous marrow also looks like antler.

 

Antler would be a good possibility, perhaps more so than opercula. So the shanks are carved from the same pieces, not attached?
And the coloration could come from the porous center taking up the finishing material, wax, or whatever, more than the outer parts.

 

All one piece buttons -- shanks are carved from the same piece. I'll go with antler!