Seaweed absorbs nutrients from the water and utilizes energy from the sun for photosynthesis. All seaweed species are simple plants and have no use for conducting tissues or roots, although some species anchor themselves to rocks.
Seaweed requires light to survive and is generally found in shallow ocean waters, providing homes and food for marine life. Some species of brown kelp form underwater forests on coastlines. Some large red species visually stand out, while other species form a low overall growth. One classification of seaweed, called the encrusting coralines, forms thin, solid, pink masses and plays an important role in cementing and building coral reefs.