At a bioluminescent web site, "milky seas" are discussed. This is where bioluminescent bacteria in the trillion-billions and beyonds cluster together and can actually be seen from space. (See blue streak next to Ethiopia in picture above). These are miles across and dozens - maybe hundreds of miles long.
This makes them - in aggregate - one of the largest organisms on Earth.
This is even mentioned in Jules Verne's 20,000 leagues under the sea.
By the way, the bright streaks are the glowing lights of cities in tis area of the world - i.e. light pollution.