The oceans are filled with giant tubular organisms that grow to the size of sperm whales. They are known as Pyrosomes or unicorns of the sea and can be nearly 60 ft in length. – WTF Fun Facts
Source: https://www.theatlantic.com/technology/archive/2013/08/12-reasons-pyrosomes-are-my-new-favorite-terrifying-sea-creatures/278316/
*Made up of zooids to form a colonial animal.
Maybe this should also specify that this isn’t an individual creature, it’s made up of thousands of tiny plankton-like creatures