1) The Earth's core is primarily composed of iron and nickel and is as hot as the surface of the sun.

2) In Norse mythology, the World Tree, known as Yggdrasil, is a massive ash tree that connects the nine realms of existence. It is considered the center of the cosmos and serves as a conduit between different realms, including Asgard (realm of the gods), Midgard (realm of humans), and Helheim (realm of the dead).

3) The ocean is home to an incredible variety of marine life, including thousands of species of fish, mammals, reptiles, and invertebrates.

4) The concept of compound interest can be attributed to the ancient Babylonians, who used it in their banking practices.