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).
1 Around 99% of the minerals in the Earth's crust are made up of eight elements including oxygen, silicon, aluminum, iron, calcium, sodium, potassium, and magnesium. 2  Common minerals include quartz, feldspar, bauxite, cobalt, talc, and pyrite. 3  Some minerals have a different colored streak than the color of their body.