Kelps are large brown algea seaweeds that make up the order Laminariales. There are about 30 different genera. Kelps grows in “underwater” forests (kelp forests) in shallow oceans, and is thought to have appeared in the Miocene, 23 to 5 million years ago. The organisms require nutrient-rich water with temperature between 6 to 14 celsioius degrees. They are known for their high growth rate – the genera Macrocystic and Nerocystic can grow as fast as half a metre a day, ultimately reaching 30 to 80 meters.