In biology, the term<unk>  or cuticula is given to a variety of tough but flexible, non-mineral outer coverings of an organism, or part of an organism, that provide protection. They are non-homologous, differing in their origin, structure and chemical composition.
Cuticle
Vesicle 
Ligament
Lumen 
Climbing fiber
Electron shell
Membrane skeleton
Reticular fiber