Glorious purple stripe jelly

While paddling for Team OCEAN on Elkhorn Slough, we encountered a very large - maybe 18 inch diameter with 3-5 ft long oral arms- purple stripe jelly very near the dairy farm, past Seal Bend. It was pulsating up and down in the water so it would come to the surface and then disappear, both delighting and frustrating the people that were trying to see it. The water was bit murky and seems very deep at that section but the white coloring with dramatic purple markings were completely visible.