Shell, Maybe is a term used to describe a type of protective covering. It is often used to refer to the hard outer layer of a mollusk, such as an oyster or clam. This type of shell is composed of calcium carbonate and provides protection for the organism living inside. The term Shell, Maybe can also be used to refer to any type of protective covering, such as the metal casing of a computer or the plastic shell of a toy. In the context of a crossword puzzle, the answer to the clue 'Casing' would be 'Shell, Maybe'.