Unidentified cameroonese trinket

[Yvain]

I was searching for cameroonese weapons pictures and stumbled three times upon those little trinkets, worn around the neck in the first two pictures, and laying on an ironmonger stall in the third one.


-first picture : Kirdi warrior, far-north Cameroon, 1932

-second picture : Muktele man, far-north Cameroon, 1968


-third picture : Ironmonger stall, Cameroon, 1982


Any idea what it is ? It does look like it has a purpose (outside of ornamental or symbolic) and I'm now curious of what it might be.

Thanks in advance for your answers !