The Dirty Projectors and Björk might not seem like the most obvious pairing, but their collaboration on Mount Wittenberg Orca is nevertheless inspired. Like Björk, David Longstreth and company share a fascination with vocal interplay, unusual arrangements, and songwriting that balances pop and experimental impulses. Indeed, it was the Dirty Projectors' involvement in a Björk tribute album curated by Stereogum.com that was the catalyst for this project, which benefitted the National Geographic Society Oceans Project. Fittingly, water is the main inspiration for these songs, which flow into one another like tributaries. The Dirty Projectors and Björk wanted Mount Wittenberg Orca to have a spontaneous feeling, so the EP was recorded in a matter of days, creating a fascinating tension between the intricate pieces and unstudied performances. Vocals are the main focus here, and the Projectors' female singers teeter between sweet coos and tart braying on the opening track “Ocean” and “On and Ever Onward,” which features Björk singing lead and showcases the avant-pop leanings of both acts to their finest; “Sharing Orb,” meanwhile, contrasts her free-form singing with structured backing vocals worthy of an operetta or ‘40s and ‘50s vocal pop. Longstreth takes the lead on the childlike-yet-complex “When the World Comes to an End” and the particularly lovely “No Embrace,” which sounds like ‘60s soul sung by mer-people. It all culminates on “All We Are,” a duet between Björk and Longstreth surrounded by backing vocals that are as beckoning and changeable as sirens. A brief but powerful statement, Mount Wittenberg Orca brings remarkably creative artists together for a good cause, and ends up bringing out the best in all of them in the process.