What are some inventions and contributions from Africa?

Except Egypt. I need some help for my class assignment. Inventions from any nation/civilization in Africa except Egypt, someone in my class took that already. Please be specific. I asked this before but everyone was linking inventions from white people (I'm not racist) and one guy was talking about... show more Except Egypt. I need some help for my class assignment. Inventions from any nation/civilization in Africa except Egypt, someone in my class took that already. Please be specific.

I asked this before but everyone was linking inventions from white people (I'm not racist) and one guy was talking about plants/animals and stuff. Didn't our black ancestors in Africa invent anything while we were there? Was it only Egypt inventing stuff?
Update: Can you also list the inventors of those things?
Update 2: I know the CAT scan was invented in South Africa by Allan Cormack, not in the Kingdom of Mutapa, Zimbabwe, or the Zulu empire. What about the rest?

http://www.southafrica.info/business/trends/innovations/inventions.htm
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