Agreed. It can be found easily in markets in my hometown (just off the coast, east of China). And it's my favorite dish. Our style is just cutting them into noodles and make it salad. https://www.google.com/search?q=%E5%87%89%E6%8B%8C%E9%B2%9C%...

Wikipedia: https://en.wikipedia.org/wiki/Rhopilema_esculentum#Use_as_fo...