Mushroom Head, by CAN.
Another song to add to the pile of must-listens: another mind boggling experimental piece that chills to the very bone.
CAN were an experimental rock band from Germany, who, much like any other truly experimental musicial artist, fused a mixture of different musical genres together to create their own sound. In Can's case they created a style of experimental music that drilled fear into the audience, rather effectively.
Mushroomhead comes from the album Tago Mago (1971), which was arguably the band's best album. Originally, Can's vocalist was Malcolm Mooney, but after an unfortunate nervous breakdown there was a vocalist sized gap left in the band. This is where Kenji "Damo" Suzuki's Can career began. The fresh input of Damo on vocals is perhaps what the band needed to create what is Tago Mago.
Often quoted as being one of the most influential albums of the 70s and modern greats, such as Radiohead's Thom Yorke and Johnny Greenwood, have cited it as a major influence on their own music.
The album in its entirety is a master-piece and is well worth a good listen, but I would recommend (after personal experience) not falling asleep to it. Unless you like waking up to high pitched screams...