Any tough but flexible non-mineral outer covering of an organism or of one part of an organism, produced by underlying living material. The similarity is only of function; different organisms may have cuticles that differ quite radically in origin, structure, and composition. For instance in Terragen organisms the cuticle might be the outer layer of dead skin cells on a human or other mammal, composed primarily of keratin, or the exoskeleton of an arthropod, composed primarily of chitin and various proteins, or the waxy coating that protects the the leaves and stems of land plants. Analogous structures also called cuticles may be found on a variety of non-Terragen organisms, though the actual materials may be quite radically different. For instance, cuticular material on the organisms of the world of Chorus typically contains chlorocarbon polymers.