Phil Lesh, who helped form The Grateful Dead in 1965, died at 84 years old Friday, according to a post on his Instagram account.

Phil Lesh, a founding member of the Grateful Dead whose bass lines powered the band’s songs over three decades and contributed to hits such as “Box of Rain,” died Oct. 25 at age 84. The death was announced in a statement posted to his official Instagram page.

Phil Lesh, bassist and founding member of The Grateful Dead, died Friday, a producer who worked with him confirmed to CBS News. He was 84 years old. A post on his Instagram account said Lesh "passed peacefully this morning.

Fans and fellow band members recognized Phil Lesh as a critical member of the Grateful Dead and he was known for his thundering lines on the six-string electric bass.