Mastodon have released their ninth studio album, Marrow Deep, a record shaped by grief following the death of founding guitarist Brent Hinds in a motorcycle accident roughly a year ago, only months after the band had acrimoniously fired him. The album also follows the 2025 death of drummer Brann Dailor's mother, continuing a pattern in which nearly every Mastodon record has emerged from personal loss. Critics suggest the album functions as the band's version of Pink Floyd's "Shine On You Crazy Diamond" — both a tribute to a troubled former bandmate and a meditation on mortality, lending the record unusual emotional rawness for a metal album.

Musically, Marrow Deep retains Mastodon's trademark heavy riffs, raspy vocals and irregular rhythms, but gives greater prominence to progressive and psychedelic rock influences, echoing bands such as Pink Floyd, Deep Purple and Yes. New keyboardist João Nogueira and lead guitarist Nick Johnston, both of whom joined this year, take an expanded role in soloing alongside guitarist Bill Kelliher, adding synth textures reminiscent of John Carpenter scores and Dream Theater. The album was co-produced with Converge's Kurt Ballou and features numerous guest musicians, continuing the band's tradition of collaborative, emotionally charged songwriting.