Leafy algae is a type of algae that grows in the ocean and is characterized by its leaf-like structure. The most common type of leafy algae is KELP, which is a four-letter word that can be found in crossword puzzles. KELP is an important part of the marine ecosystem, providing food and shelter for many species of fish and other marine life. It also helps to protect coastlines from erosion and provides a habitat for many species of invertebrates.