Kamo Aquarium recently started the exhibition of Flower Hat Jellies (jp: hanagasakurage ハナガサクラゲ), scientific name: Olindias formosa, a very rare species of jellyfish that can be found in Southern Japan's water (Kyûshû), or in Brazil and Argentina's waters too. This jellyfish's tentacles release a fluorescent protein called Gamillus (GFP) that glows green under ultraviolet light, which makes all the beauty of this species.
By the way, formosa means "beautiful" in latin. That jellyfish totally deserves its name.