Sufjan Stevens, the Chicago-based rapper Serengeti, and hard-to-classify experimental musician Son Lux have just released a song called "Museum Day," which they recorded under the collective name s/s/s. The unlikely supergroup grew out of Serengeti's invitation to Stevens to provide some material he could incorporate into his album, presumably because he thought it would be fun to work with the least likely rock artist to appear on a rap album, and Stephin Merritt didn't return his calls. After Serengeti added his vocals to Stevens' contributions, he apparently decided that the results were too weird to mesh with what he was already working on, so he had the brainstorm of sending them to Son Lux, in the hope that he could make them even weirder. That he may have succeeded is a no-brainer. The full results will be released on March 20 as a 4-song EP titled Beak & Claw.