A coiled snake helped give Metallica's 1991 album its nickname, The Black Album.
The original cover shows Metallica's logo angled in the upper-left corner and a coiled snake in the lower-right. Both emblems were embossed so subtly against the black background that they were difficult to see, creating the stark appearance that inspired the familiar nickname. The snake derives from the Gadsden flag, whose motto is "Don't Tread on Me."
The album is officially titled Metallica, not The Black Album. The nickname became widely used because the self-titled record's nearly black packaging was visually distinctive and separated it from the band's earlier, more elaborate covers. The phrase "Don't Tread on Me" also appears as the title of one of the album's songs.
Later editions use dark gray emblems that stand out more clearly than the original embossed design. The cover's minimal look was also jokingly compared with Spinal Tap's fictional album Smell the Glove in the documentary A Year and a Half in the Life of Metallica.