The flower hat jelly (Olindias formosus) is a species of hydrozoan in the family Olindiidae. Although they look like a jellyfish, they actually belong in the class Hydrozoa, while true jellyfish belong in class Scyphozoa. Flower hat jellies occur in the western Pacific off southern Japan. Characterized by lustrous tentacles that coil and adhere to its rim when not in use, the flower hat jelly's bell is translucent and pinstriped with opaque bands, making it easily recognizable. The flower hat jelly can grow to be about 15 cm (6 in) in diameter. It lives around 4–6 months. Its diet consists mostly of small fish, which are caught with the tentacles. Its sting is painful, but is not deadly to humans. It is powerful enough to leave a rash.