Ntama Coumba:a beautiful african seed

Ntama Coumba is an african seed that i use a lot in my jewelry.
I like to use it my necklaces as a spacer because of its flat and oval shape.
Dark brown i like the way it contrasts with my glass beads or metal beads.
I found very little information about the origin of the seed.
If someone know from what tree it comes from please contact me :
i would love to learn more about those seeds!