It's hard to tell from the pictures but they could be plastic.
Seem a bit too rounded and thick compared to most ivory I've seen. Could you take a picture from the side to see how thin they are. If they're very thin it's most likely ivory as that'll have the required strength.
You can also do a hot pin test if you don't care about causing a blemish if they turn out to be plastic.
As far as bone goes, if it doesn't have pores it wouldn't be bones. Check with a magnifying glass though.
Hope this helps