These graceful and alienesque critters are named Hydra viridissima and are among the main representatives of freshwater Cnidarians, a primitive animal group that includes jellyfish, corals and sea anemones. Hydras are found in all continent across the Earth except for Antarctica and are one of the simplest multi-cellular forms of life known to humanity. Their green colour is due to a symbiotic relationship with Chlorella, a green algae that lives inside the hydra’s cells producing sugars from sunlight and giving some of this precious energy to the hydra in exchange for protection against predators and a well-suited environment!