Kelp
Kelps are large brown algae seaweeds that make up the order Laminariales. There are about 30 different genera.
Kelp
Kelp 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 temperatures between . They are known for their high growth rate—the genera "Macrocystis" and "Nereocystis" can grow as fast as half a metre a day, ultimately reaching .