1) The Amazon rainforest produces more than 20% of the world's oxygen.

2) The world's oldest living plant is believed to be a clonal shrub called "Old Tjikko" in Sweden, estimated to be over 9,500 years old.

3) The largest living structure on Earth is the Great Barrier Reef, spanning over 2,300 kilometers (1,400 miles) along the coast of Australia.

4) The first modern health insurance policy was introduced in Germany in the late 19th century.