Seaweed is a microorganism that grows in oceans, lakes, rivers and other bodies of water and is comprised of algae. Algae is a plantlike organism that doesn’t contain actual roots, flowers, leaves and stems, but does contain the green pigment known as chlorophyll. This allows the organisms to grow through the process of photosynthesis. Seaweed can include members of green, red or brown algae families, and there exist around 10,000 species within many marine habitats around the world.

Some forms of seaweed appear as long strands and branches, while others look like sheets. A root-like part of seaweed called the holdfast is used to attach it to rocks and other marine objects, but does not act like a true root since it does not contribute to its growth. Seaweed can grow in massive quantities in various places from the poles to the equator. It is used by many other marine animals as a source of food as well as a location for mating.

Kelp is a large type of seaweed that has large leaf-like protrusions known as fronds and can grow as long as 200 feet (61 M). Gulfweeds, or sargassum, are a type of brown algae that grow in warmer water and can float in large masses, particularly in an area known as the Sargasso Sea. Types of seaweed that are comprised of red algae are generally smaller and more delicate, and appear to have many branches.

Seaweed has many uses for different types of products around the world. One of the major uses is for food, as it can be quite rich in nutrients, vitamins and minerals. People living on coasts use seaweed to make noodles, bread, drinks and more. Another popular use is when sheets of dried seaweed are used to wrap sushi.

Two things that can be extracted from seaweed are agar and carrageenan, which are used throughout food, drug and other industries. Carrageenan is used to help make paper and toothpaste, among other things, while agar can be used as a thickening agent in foods. Agar is also used widely in laboratories to help grow bacterial cultures. Seaweed can also be used in beauty products, medicine, animal food, fertilizer, and more.