What is the name for a skeleton that is located on the outside of invertebrate bodies?

An exoskeleton is the correct term for a skeleton that is located on the outside of invertebrate bodies. This structure provides protection and support for the organism, much like a shell or outer casing. It is primarily made of a hard material, often chitin for arthropods, which helps prevent water loss and supports the structure of the body.

In contrast, the other terms refer to different types of skeletal structures. An endoskeleton is located within the body, providing internal support, as seen in vertebrates. Cartilage is a flexible connective tissue that makes up parts of the skeletal system but is not a skeleton itself, and bone structure refers specifically to the solid material that makes up the skeleton in vertebrates—mostly found in endoskeletal systems. Each of these structures serves different functions and is adapted to the specific needs of the organism in question.