Pharrell Williams Fans Shocked He's Turned 50, Want His 'Fountain of Youth'

Pharrell Williams turning 50, while not looking a day over 30, is absolutely baffling to his legion of fans ... who want to know the secret behind his half-century milestone.

PW had his big birthday on Wednesday, and a ton of people online wished him well on another year around the sun, and many couldn't help but point out the obvious -- the dude just doesn't age!

It was a wide range of responses, but all pointed to the supposed fountain of youth the hip hop legend must be drinking from on the daily.

One fan asked Pharrell for his elusive skincare routine, while another said, "How is it possible that I appear older than Pharrell Williams? ... Who is literally 50 years old."

If you've been under a rock for the last 30+ years, Pharrell's been in the music biz since the early '90s ... forming the group The Neptunes in high school and getting discovered by producer Teddy Riley.

He went on to work with huge names like Madonna, Jay-Z, Shakira, Justin Timberlake, Gwen Stefani and Daft Punk -- while dropping his own iconic tracks, like "Happy," too.

Maybe he's born with it ... or maybe he's just found out how to get lucky. HBD!