Noisecreep is reporting that Mastodon is currently working on their fifth full-length. In the piece, drummer Brann Dailor talked about the sound of the new material so far:

"It doesn't seem as proggy. There's moments, but it seems more riff-oriented. It seems a little more stripped down. [2004's] 'Leviathan' was a little more stripped down, and it feels like that to me. Everything always changes once you go in the studio, but at the moment it seems like a really super-heavy Led Zeppelin or something. It has a lot of that [John] Bonham-esque groove to it, but really heavy and dark. I really like playing like that, and when it goes into those parts, I'm psyched."

The band last released Crack the Skye in 2009.