Featured Japanese carved Camellia brooch- what is this？

I checked again, those are not pin holds but dust

 

but..... I'm not tethered to that call.......

 

I see those straight lines here..

 

I also noticed that there’s some white layer beneath the metal pin, which looks similar to the outer shell of these examples, might be the remaining part that was not fully polished off (deliberately left there to indicate what it is maybe?)

Also the color variation seems to match too… so I’m convinced & contented

 

The image of the pin just above here LOOKS like it's showing 'shreger lines', but then they're pretty darned straight also......so, I dunno!!​

 

I guess it’s just all teeth having similar texture. It feels different in person, and I would say, finer than most of the ivory objects I’ve seen