CocoRosie : Biography
From Wikipedia -
CocoRosie is an American musical duo formed by sisters Bianca Leilani "Coco" and Sierra Rose "Rosie" Casady in 2003.
Sierra mainly plays the guitar, piano and harp, and contributes vocals. Bianca sings and manipulates various children's toys/electronic & percussion instruments. CocoRosie performs as a duo and also with other backing musicians on occasion, usually a bassist and either a drummer or beatboxer. They were active for most of 2004, 2005 & 2006 playing dates across the US and making several trips to Europe for tours playing with TV on the Radio, Bright Eyes, Devendra Banhart and others.
In late 2006 they appeared as a featured act at the Touch and Go Records 25th anniversary block party in Chicago along with Big Black, Scratch Acid, Killdozer, The Ex, Uzeda and many others.