Unlike insects, spiders have an endoskeleton in addition to their exoskeleton. Some animals, such as the tortoise, have both an endoskeleton and an exoskeleton. The echinoderm skeleton is an endoskeleton that is enclosed by the epidermis. The dermis contains an endoskeleton of calcium carbonate components known as ossicles. An endoskeleton derived from the mesoderm is present in echinoderms, sponges and some cephalopods. Bones are rigid organs that form part of the endoskeleton of vertebrates. The Weapon X program was responsible for Wolverine's adamantium endoskeleton and fabricated memories. Just below their skin is an endoskeleton composed of calcareous plates or ossicles. A true endoskeleton is derived from mesodermal tissue. This endoskeleton is composed of plates called ossicles. An endoskeleton is a skeleton that is on the inside of a body. The larvae form a sophisticated endoskeleton that is made of two spicules. During early embryonic development the endoskeleton is composed of notochord and cartilage. The vertebrate endoskeleton is basically made up of two types of tissues (bone and cartilage). This technique was used for the endoskeleton in "The Terminator".