Poseidon mangrove

Poseidon mangroves (Arbormarina insula) are the largest tree-like organisms known to exist, dwarfing Earth's redwoods. Mangroves grow directly from the seafloor, where the massive prop roots send out shoots and runners that grow into more trees. A single mangrove stand can result in hundreds of square kilometers of forest, most of it (being a living organism) not on geographic maps.