* Phytoplankton: These are microscopic plants that float in the water. They are the primary producers in the ocean, meaning that they are the first organisms to convert sunlight into food.
* Kelp: These are large, brown algae that can grow up to 100 feet long. They are found in cold, nutrient-rich waters.
* Sargassum: This is a type of brown algae that floats in the Sargasso Sea. It is a major habitat for many marine organisms, including sea turtles, fish, and crabs.
* Coral: These are tiny animals that build hard skeletons out of calcium carbonate. They live in colonies and can form large reefs. Coral reefs are important ecosystems that provide food and shelter for many marine organisms.