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).
Rocks. A rock is a mixture of one or more minerals. They are classified by the way that they are made. Monominerallic-a rock made of only one mineral. In this case, the rock is both a rock and a mineral. Polyminerallic-a rock made from more than one mineral.