Which two visual elements were embossed on the original cover of Metallica's 1991 album?

The original cover of Metallica featured an embossed snake and Metallica logo.

The artwork used a nearly black background, with the band's stylized logo and a coiled snake placed so subtly that both could be difficult to see at first glance. The restrained design gave the self-titled album its enduring nickname, The Black Album.

The snake is commonly associated with the Gadsden flag and the phrase “Don't Tread on Me,” which also appears as the title of a song on the record. The cover therefore connects the album's visual identity with one of its musical themes.

The design is sometimes described simply as an all-black cover, but that leaves out the faint embossed details. Those two elements are the key visual features of the original packaging.