“Altar” is a true collaboration album between SunnO))) and Boris that is a result of both bands conceptualizing, writing and recording the album together as one entity. Both groups have stepped outside their previous sounds and created a wholly unique album that stands on its own unique ground. There are elements of each group's trademark sound within the album but true to each group's progressive and experimental aspects, “Altar” moves into a completely new dimension. Also contributing additional entrancing textures are the guest collaborators on this album including:
• Jesse Sykes (Jesse Sykes and the Sweet Hereafter) vocals on “The Sinking Belle (Blue Sheep)”.
• Kim Thayil (Soundgarden) guitar on “Blood Swamp”.
• Joe Preston (earth, Thrones, Melvins, High on Fire) vocals on: “Akuma No Kuma”.
• Dylan Carlson Earth guitar on "Her Lips Were Wet With Venom (Satan Oscillate My Metallic Sonatas)".

Also: Bill Herzog, Phil Wandescher (Jesse Sykes and the Sweet Hereafter), Rex Ritter (Jessamine, Fontanelle), Tos Niewenhuizen (Beaver, GOD), and Steve Moore (earth).

Possibly unbeknownst to some is that there are THREE versions of the song, "The Sinking Belle". The version: "The Sinking Belle (Blue Sheep)" appears on the domestic and Japanese versions of the CD and 3xLP. "The Sinking Belle (Black Sheep)" appears ONLY on the Japanese version of the CD. "The Sinking Belle (White Sheep)" appears ONLY on the Japanese 3xLP box set. Also, the track, "Her Lips Were Wet With Venom (Satan Oscillate My Metallic Sonatas)", appears on the Japanese and domestic 3xLP box sets and as well as the limited 2xCD versions. Read more on Last.fm. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.