Incredible But True Incredible But True Human World History Makers Cities Of The World Art And Music Sporting Headlines Plant Life Fish, Amphibians, Reptiles Birds and Mammals Creepy Crawlies Marine Life Restless Earth Earth's Secrets Changing Weather Seas And Oceans Comparisons Amazing Structures Machines And Man World Of Inventions Travelling Around Mysterious Universe	All Different All snowflakes are based on the shape of the hexagon, but no two snowflakes of exactly the same shape have ever been found.   Previous: Back Book: Incredible But True Section: Incredible But True Chapter: Changing Weather