A matrioshka brain[1] is a hypothetical megastructure proposed by Robert Bradbury, based on the Dyson sphere, of immense computational capacity. It is an example of a Class B stellar engine, employing the entire energy output of a star to drive computer systems.[2] This concept derives its name from the nesting Russian Matrioshka dolls.[3] The concept was deployed by its inventor, Robert Bradbury, in the anthology Year Million: Science at the Far Edge of Knowledge, and attracted interest from reviewers in the Los Angeles Times[4] and the Wall Street Journal.[5