1) The study of fossils is called paleontology, and it helps us understand the history of life on Earth and the process of evolution.

2) The Great Barrier Reef, situated off the coast of Queensland, Australia, is the largest coral reef system in the world. It stretches over 2,300 kilometers (1,400 miles) and is home to a diverse array of marine life, making it a popular destination for diving and snorkeling.

3) The world's oldest known living tree is a bristlecone pine named "Methuselah" in California, estimated to be over 4,800 years old.

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