The flower hat jelly (Olindias formosa) is a species of jellyfish occurring in the West 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 inches) in diameter. Flower hat jelly fish live short lives, approximately 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.