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	Glow In The Dark Sea pens grow on the sandy seabed off southern Australia. Shaped like giant quill pens, they glow at night with a bright purple luminous light. The sea bed can be full of spectacular colours   Previous: Back Book: Incredible But True Section: Incredible But True Chapter: Marine Life