Moon?

It was on a sand beach where lots of small (0.3 to 3cm) jellies washed up. They where clear apart from four purple rings that unlike the moon jelly went right down to the rim of the bell and stopped there. The short tentacles where purple. The tentacles where about 1cm long. It had no sting. At the centre of the bell there was a clear tube that came down about 1.2 cm