Stephen O’ Malley and Greg Anderson’s superior drone-metal project are back.

It’s been four long years since Sunn O)))‘s masterful Monoliths & Dimensions, although, in lieu of a new studio album, they’ve nudged out a smattering of live releases and demos in the interim. 2011 saw them collaborate on a full-length LP with spiritual forefather Nurse With Wound, and next year will, we’re told, bring another collaborative full-length – this time with Norwegian metal institution Ulver, who have been turning out experimental metal for over two decades (see 1995’s exceptional, folk-inflected debut Bergtatt).

Terrestrials will feature three long-form pieces from the two camps. Anderson’s Southern Lord label promise three “movements” of “sonically uninhibited, unpredictably cosmic” drone-rock. Ulver’s last LP was this year’s classically-inclined Messe 1.X-VI.X, and the label suggest that Terrestrials will see both parties on particularly ambitious form.

Terrestrials will touch down to earth in February 2014. That’s the cover art below.