A: According to BBC, an endoskeleton is a bone structure located in the interior of an animal, and an exoskeleton is a bone structure located on the exterior of an animal. Each type of skeleton has unique advantages and disadvantages in helping the animal survive.
Minerals made of only one element are called NATIVE minerals (i.e., silver, gold, mercury, copper). Minerals composed of compounds are simply referred to as minerals (i.e., quartz, which is made up on silicon and oxygen).
Minerals are usually solid, inorganic, have a crystal structure, and form naturally by geological processes. The study of minerals is called mineralogy. A mineral can be made of single chemical element or more usually a compound. There are over 4,000 types of known minerals. Calcite, which is common in seashells, is a carbonate mineral. 2  Oxides include the minerals from which most metals, such as tin and copper, are refined. 3  An oxide consists of an element, usually a metal, joined to oxygen.