Ivory -carved elephant Bridge

I have recently inherited what appears to be three Ivory carvings - elephant Bridges.

These were given to my Uncle as a gift in Africa in the 1970s when he was working as a Comboni Missionary

I am looking to find out as much about these pieces as possible - apologies I am definitley an amateur when it comes to these things.

i suppose questions I have are:

Is it Ivory?

How. To know what year it's from?

Are they of any value?

i can upload more detailed pictures if necessary.

Fair