Bet you never played a sanza, or even think you heard one before. But if you’ve ever given the OutKast classic Aquemini a spin (remember the opening “Hold On, Be Strong”?)—or any album in Earth, Wind & Fire’s catalog, for that matter—then you know the sanza well. The African thumb piano goes by many different names throughout the continent, including mbira, kalimba, likembe, chisanji…and sanza. Recently in Phoenix, Arizona, the Musical Instrument Museum kicked off “Sanza: African Thumb Pianos from the Collections of F. & F. Boulanger-Bouhière and MIM.” Over 200 stanzas are currently on exhibit in the museum’s Target Gallery till October, on loan from a private Belgian collection.

Nowadays, singer Erykah Badu mesmerizes live audiences by pounding out rhythms on her futuristic Yamaha beatbox like a cafeteria table. But at industry showcases before the release of her Baduizm début, she sometimes plucked at a rectangular wooden sound box with metal keys as a segue between hits like “Next Lifetime” and “Apple Tree.” The MIM exhibit displays plenty of sanzas like Badu’s, alongside others with larger tortoiseshell sound boxes (called resonators). Many of the sanzas boast intricately elegant symbolic carvings meant to honor African ancestors.

Earth, Wind & Fire founder Maurice White first fell in love with the sanza early in his career, singing with the Ramsey Lewis Trio. In the late 1960s White unearthed a kalimba in a Chicago drum store and quickly learned how to master the instrument. “Uhuru,” off the Ramsey Lewis Trio’s 1969 Another Voyage, featured the first recording of White playing the sanza. White has been forever linked with its sound, soloing through Earth, Wind & Fire songs like “Kalimba Story,” “Departure,” “Biyo” and “Evil.” Thumb pianos just like White’s from Nigeria, Tanzania, Botswana, Mozambique, Cameroon and the Ivory Coast are represented in the MIM’s exhibition.

The sanza has traditionally accompanied African praise songs honoring ancestors and revered chiefs for centuries. As a major instrument of the Motherland, the sanza is as central to African music as the guitar is to American rock ’n’ roll or the accordion is to classics in France. Still think you haven’t heard it? Take a listen.