Possibly a purple sea stinging jellyfish.

Also known as the colorful golden jellyfish, the outer umbrella has purple bands, purple tentacles, and the diameter of the umbrella can reach more than 30cm. Jellyfish have purple bands on their outer parachute, purple tentacles, and a diameter of 30cm or more. Jellyfish are invertebrates and belong to the phylum Coelenterata.

The purple stinging jellyfish has four oral tentacles and eight marginal tentacles, and its dorsal purple stripes are striking. The Purple Sea Sting Jellyfish usually lives with a parasitic crab***.