Red Hot Chili Peppers bass player Flea gave an amazing music lesson to an unlikely student when he spent some time with Koko the gorilla.

Koko, the famed primate who has mastered a form of sign language that allows her to communicate with humans, is fascinated by Flea’s bass, plucking out notes on the instrument while experimenting with it.

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“This is just the greatest thing that could ever happen. This is the day that I will never forget in my life,” Flea says in a video posted on the Red Hot Chili Peppers’ YouTube channel.

“One of Koko’s favorite musicians, Flea from the Red Hot Chili Peppers came to visit,” the Gorilla Foundation wrote on its website. “Koko was thrilled by the mellow sounds and a jamming session followed with Koko strumming on Flea’s bass!”