Dear Ruth,

My apologies about my late reaction.
What you have here is a lovely Japanese netsuke. This netsuke were worn on Japanese kimono as a belt button or button-like toggle on garments—robe.
Here you can find some information:

https://en.wikipedia.org/wiki/Netsuke

Indeed your Netsuke is carved in Ivory. Its well carved and has nice expression. Many of these netsuke's are made in later times in Hongkong to meet the demand but I believe yours is an original from Japan made early 20th century. If you would consider selling it be aware that CITES rules are in place for this type of ivory objects. Therefor I recommend to ask a good auction house to care of proper measures in order to sell this in the right way. If your Netsuke came to auction I believe it would make around the estimate I gave.