Egg capsules, which are protective casings that contain developing eggs, can be referred to using a variety of different synonyms. Commonly used terms include egg cases, egg sacs, spawn, roe, caviar, and ova. Egg capsules are commonly found in a variety of different animals, including insects, mollusks, fish, and various marine invertebrates. Depending on the species that produces them, these protective casings can have a wide range of different shapes, sizes, and colors. While their purpose is primarily to protect and nourish developing eggs, egg capsules can also serve as a source of food for other animals in the ecosystem.