Any of several species of adaptable, intelligent terragen rodent. All through history rats have proved adaptable and were one of the few types of animals to thrive with the ascendence of baseline hu. Easily kept and bred, they are popular with geneers and spacers, and it is estimated that several million species have been created, hybridized, or have evolved naturally, in the period since mindkind first ventured into space. Rat splices, rat tweaks, and ratborgs have proved their worth on ships, especially relativistic and pioneer vessels, many time, and often develop into unique and indigenous ecosystems. Rat provolves are also common; although not as common as cat or dog provolves.