The Pandorica Opens
This novel sees the first appearance of the Chelonians, a race of cybernetic humanoid tortoises who appeared subsequently in other spin-off novels and are referenced in "The Pandorica Opens". The Chelonians are war-like, hermaphroditic and lay eggs. They have cybernetic enhancements that include X-ray vision and improved hearing, but this advanced state of technology often causes them to consider human-beings as a form of parasite to be removed.