In ideal conditions, kelp can grow up to 18 inches per day, and in stark contrast to the colorful and slow-growing corals, the giant kelp canopies tower above the ocean floor. Like trees in a forest, these giant algae provide food and shelter for many organisms. Also like a terrestrial forest, kelp forests experience seasonal changes. Storms and large weather events, like El Niño, can tear and dislodge the kelp, leaving a tattered winter forest to begin its growth again each spring.
(Original source and more information: NOAA National Ocean Service Ocean Facts)