If you are talking about the earth, the crust is the outter side of the earth made up of minerals, particularly rocks such as metamorphic and igneous rocks. It is three times as thick under dryish land than under the sea. The core is at the very center of the earth. It is thought to be made of iron and nickel and it is so hot from all the compactness and no one, i repeat, nop one can ever dig deep enough to get there(and no, I didn't copy and paste. I knew this already)
