Professional ratings
Aggregate scores
Source	Rating
Metacritic	77/100
Review scores
Source	Rating
About.com
Allmusic
Blabbermouth	8.5/10
Consequence of Sound	B-
Drowned in Sound	7/10
The Guardian
NME	8/10
Pitchfork	6.9/10
The Quietus	favorable
Sputnikmusic

Terrestrials is a collaborative studio album by American drone metal band Sunn O))) and Norwegian experimental music group Ulver. Produced by Stephen O'Malley and Kristoffer Rygg, it was released on February 3, 2014, via Southern Lord Records. It has been described as "three live improvisation pieces".

On December 10, 2013, a sample from the closing track, "Eternal Return", was released for streaming. It was also streamed on Pitchfork Advance on the day it was released until February 10, 2014.

The relationship between Ulver and Sunn O))) extends to the mid-1990s, when Stephen O'Malley interviewed Kristoffer Rygg for various magazines. Ulver produced a track on Sunn O)))'s White1 and O'Malley played with Rygg and Daniel O'Sullivan, also of Ulver, in the ambient/noise band, Aethenor. Sunn O))) was invited to perform at the Øya festival in Oslo, at which time Rygg proposed that the band remain in the country for several additional days in order to collaborate. The bands created "the foundations for a bunch of tracks" at Ulver's studio, Crystal Canyon, and then Ulver prepared the preliminary arrangements and mix. The bands collaborated on the production, which, as O'Malley explained,

took a while because we don't live in the same country and everyone's just really busy. I got to be honest, for a while it wasn't a priority. It was something we were doing because we enjoyed each other’s company and we enjoyed the music but it wasn't like the new album of either band. It didn't have that urgency to it. Also, I think the music, the pacing and the feeling of the music itself kind of suggests that too.

As O'Malley explained of the three "live improvisation pieces" comprising the album, "I remember the vibe in the room back then was more rāga than it was rock. And despite the fact that the walls were literally shaking from volume, it was actually quite a blissed out, psychedelic session. I wanted to preserve that vibe in the final mix".

...
Wikipedia