Call of the Mastodon, a 2006 collection of Mastodon's first-ever forays into the recording studio, exposes the humble beginnings of hard rock's heaviest hitters. The nine tracks laid to tape here, the first the fledgling quartet had ever written, document a band finding its own voice and place in the musical world. The compilation collects all of the band's earliest material including demo material, 2001's Slick Leg 7", and 2001's Lifesblood EP. Call of the Mastodon is a vital piece of heavy metal history and the crucial starting point in the still burgeoning Mastodon legacy.