Yoruba thumb piano, made from large lightweight wooden box (approx 20x15x8 inches)and wide metal blades. Used percussively as well as melodically. Often accompanied with Selli rattles
These instruments are usually tuned to play the role of a speaking voice in the music, rather than to melodically match a musical scale.
View the famous Fatai Rolling Dollar(R.I.P.) playing agidigbo here: