This is a food additive made from kelp and this is only one thing you can do with kelp. Kelp is a type of large seaweed. There are around thirty different types of kelp and it is called a weed because it grows so quickly.
Kelp grows underwater and can be found in kelp forests. Just like a forest of trees on land you have large groupings of these plants and it does have a resemblance to tree forests.
Kelp is a good food source and some countries use it as a staple. This makes it a renewable food source.
There are scientists working on kelp as a renewable fuel source. The methane produced from decaying kelp can be harvested and the sugars in kelp can be converted into ethanol.