Seaweeds themselves have many forms, including those that appear as if they are terrestrial plants with leaves and stems, looking like moss, mushrooms, leaf lettuce, or even a palm tree.
Kelp is known for its high growth rate and is the largest seaweed.
Some biologists prefer the term "marine macroalgae" over "seaweeds."
Seaweeds are also harvested or cultivated for the extraction of alginate, agar, and carrageenan, gelatinous substances collectively known as hydrocolloids or phycocolloids.
A number of research studies have been conducted to investigate claims of seaweed's effects on human health.
Seaweeds are popularly described as plants, but biologists typically do not consider them true Plantae.
The pharaoh also wore a striped headcloth called the nemes.
Seaweed serves a number of ecological, commercial, and medical uses.
Seaweeds are classified into brown algae (Phaeophyta), red algae (Rhodophyta), and green algae (Chlorophyta).
Few are actually seaweeds, however, either because they are freshwater or microscopic.
Single-celled or few-celled organisms are not usually called seaweeds.
Chondrus crispus (commonly known as Irish moss or carrageen moss) is another red alga used in producing various food additives, along with Kappaphycus and various gigartinoid seaweeds.
Rather than a specific taxa, seaweed can be one of several types of algae: brown algae, red algae, or green algae.
One example of brown algae seaweed is Sargassum, which creates unique habitats in the tropical waters of the Sargasso Sea.
Various seaweeds serve as a habitat and food for other sea creatures.
Through the nineteenth century, the word "kelp" was closely associated with seaweeds that could be burned to obtain soda ash (primarily sodium carbonate).
Seaweeds are often confused with other photosynthetic organisms.
Some seaweeds have gas in the fronds that help them to be buoyant and float at or near the surface.
Seaweeds are extensively used as food by coastal peoples, particularly in Japan and Korea, but also in China, Vietnam, Indonesia, Peru, Taiwan, the Canadian Maritimes, Scandinavia, Ireland, Wales, Philippines, and Scotland, among other places.
The red algae (Phylum Rhodophyta, from Greek rhodon = rose + phyton = plant, thus red plant) are a large group of mostly multicellular, marine algae, including many notable seaweeds.