Final answer:
Bones and teeth have the highest mineral density in animals, with calcium and phosphorus being the major minerals that contribute to their hardness. Other minerals like magnesium and trace minerals also play a role in the density of bones and teeth.
Step-by-step explanation:
In the animal kingdom, the part with the highest mineral density is the bones and teeth. Calcium and phosphorus are the major minerals found in bones and teeth, which make them hard and strong. Other minerals like magnesium and trace minerals also contribute to the density of bones and teeth. For example, sea urchins have teeth made of calcite, a form of calcium carbonate, which is very dense.