The mbira is the classic instrument of Zimbabwe, with an entire musical genre developed around it. It consists of approximately 20-24 flattened metal prongs which are fastened at one end to a wooden resonator body (usually some sort of box shape). The mbira sits in a calabash (gourd) which acts as it's resonator. The free ends of the metal prongs are plucked with the thumb of the left hand and the thumb and index finger of the right hand. The most important feature of mbira music is its chiming, cyclical nature, with each new repetition varying slightly from the last.
If you'd like to learn more about marimba and mbira music you might consider subscribing to Dandemutande.
Or try Soloman Murungu's excellent Mbira HomePage.