The band's sixth studio album also entered the charts in the Top 10 in most European markets and top 20 in most remaining territories. Once More 'Round the Sun is also the No. 1 rock/metal album in the U.K.-another first for the guys.

Mastodon guitarist and "Golden Axe" Explorer creator Bill Kelliher says he took a "less is more" approach to the guitar lines for Once More 'Round the Sun.

"There have been some records we've done where I'm laying tons of guitars all over the place, and not to say I didn't do that again, but every time I went into the studio, I tried to get the best guitar tones possible and really focus on that," he told Gibson.com.