Martha frowned, upset at that. "No aliens? How do you survive as just humans?"
She had no idea how to describe the Face of Boe. Other than a giant face. In a bubbling jar. Who died to save a city. She waved a hand, "It's like reavers, maybe. He used to be human, they think. Once upon a time. But he's just a face now. Or was. He died. But reavers? We never came across those."