<span> It is called the Calvin Benison Cycle</span>
The two substances are rock (molten and solid) and metal (solid + liquid).
Layers of the earth from the outside in:
1. crust. hard rock/dirt/ground. Shell
2. mantle. melted rock and stuff. Egg white
3. core. Outer core - liquid. Inner core- solid. Nickle and iron. Yolk
To grow food to grow food
