cast
From ZooTerms (Dictionary of Invertebrate Zoology)
cast (noun; Old Norse kasta, throw): 1. Anything that is shed in a form resembling the original.
2. (Annelida: Oligochaeta) The excrement of an earthworm.
3. (Arthropoda: Insecta) The molted exoskeletons of arthropod instars.
4. (Mollusca) An extraneous substance molded in the interior of a fossil shell, the shell itself having disappeared.
