Egg-case is a term used to describe the protective covering of eggs. However, there are several synonyms that can be used to describe this term and they include egg sac, egg pouch, egg capsule, egg clutch, and ootheca. Ootheca is a more specific term used to describe the egg case of some insects such as cockroaches and praying mantises. An egg sac is used to describe the protective covering of spider eggs. Egg pouch is used to describe the egg case of some fish species. Egg capsule and egg clutch are used interchangeably to describe the protective covering of eggs laid by certain aquatic animals such as sharks and skates.