Marrus Orthocanna Is A Colony That Functions As One Animal
Portuguese Man-Of-War is a special kind of creature that isn’t one kind of creature at all; it is a collection of several animals that function together as if they are one animal. Marrus orthocanna is a microscopic, and less well-known, version of the same thing.

This strange aquatic animal (animals?) is a collection of polyps and other creatures that contract and expand in concert, thereby propelling the micro-organism through the frigid Arctic waters. It is kind of like a rocket that functions in stages, and its tail even resembles the exhaust of rocket fuel.