Pretty much anything released by the prog-rock outfit the Mars Volta is destined to be both a mind- and ear-bending affair, but there was a unique kind of musical nuttiness happening on Amputechture, the group’s third full-length. The record, which was released on Sept. 12, 2006, was the band’s first album without a singular unifying narrative, resulting in a dizzying array of ideas and themes, performed by an eclectic cast of players.

Produced by guitarist/chief mad scientist Omar Rodríguez-López, Amputechture is 76 minutes of decidedly out-there rock-jazz-fusion, over which singer Cedric Bixler-Zavala weaves a series of varying lyrical themes, focusing predominantly on the effects of religion on the world. To this day the record stands out as a unique chapter in the Mars Volta’s discography, and remains a polarizing subject of debate among fans, who tend to either love or hate it.

Part of that stems from the admitted self-indulgence of Amputechture, which band members have since referred to as their “autistic child,” because it is the album that’s the least relatable to others, but also the one its creators nurtured the most. And as an album, it’s also a lot to process: There’s really a broad swath of musical tidbits within, culled from both new compositions as well as previously unrecorded leftovers, dating as far back as the band’s former life as At the Drive-In.

One of the album’s standout tracks and a perennial live favorite, “Viscera Eyes,” was originally written by Rodríguez-López while in At the Drive-In. Another live staple, “Day of the Baphomets,” recycles lyrics and the melody from “A Plague Upon Your Hissing Children,” an unreleased track from De-Loused in the Comatorium. There was a boatload of new material, too; Bixler-Zavala’s new lyrics on the record ran the gamut, from recounting U.S. immigration marches to stories of possessed nuns.

The album also stands out as an intriguing time for their personnel. In addition to Rodríguez-López, Bixler-Zavala, bassist Juan Alderete and drummer Jon Theodore (in his final recorded performance with the band), former ATDI/Sparta guitarist Paul Hinojos made his first studio appearance with the band, while John Frusciante (Red Hot Chili Peppers) was recruited to play lead and rhythm guitars. Both Hinojos and Frusciante would remain important collaborators on later works with the Mars Volta.

As with fans, critical response was largely mixed, although reviews mostly tended toward favorable, garnering a Metacritic rating of 61/100. Blender awarded the record 4 of 5 stars, yet Pitchfork rated it 3.5/10. Entertainment Weekly ranked it a solid ‘B,’ while NME rated it just 5/10. Billboard, which found Amputechture to be fairly average, remarked it “isn’t for casual listening, so those checking out the Mars Volta for the first time should take it slow to prevent a sonic hangover.” The same can be said for longtime fans, some of whom are still digesting the album.

That said, it did perform admirably, considering its challenging nature. Amputechture debuted at No. 9 on the Billboard 200, selling more than 59,000 copies in its first week. By 2009, it had already sold an estimated 400,000 copies. In hindsight, considering the band’s next album—The Bedlam in Goliath—would be inspired/disrupted by an evil Ouija board, Amputechture almost seems somewhat normal. For the Mars Volta, at least.

When taking stock of the band’s deep catalog of music, Amputechture doesn’t always jump out first among favorites like Deloused in the Comatorium and Frances the Mute, but over time the record has become a true sleeper that continues to reward intrepid listeners. As seen time and again, it’s always the albums that are the hardest to “get” at first, that stay with us the longest.

22 Modern Musicians Frank Zappa Would Have Loved

More From