In combining the virtuosic musicianship of Led Zeppelin, the conceptual wizardry of Rush, and the crushing sludge of Neurosis, Mastodon created a foundation for 21st-century metal. (In fact, Neurosis guitarist/vocalist Scott Kelly appears on almost every Mastodon album.) Frontman Brent Hinds’ vocal style harkens back to Ozzy Osbourne and his band has regularly paid homage to its forefathers with striking ZZ Top, Thin Lizzy, and Metallica covers.