Environmental Graffiti has a great round-up of the world's most gorgeous jellyfish, including the porpita porpita seen above. OK, technically, this one is not actually a jellyfish, but it is categorized in the same phylum and it certainly looks close enough (and is pretty enough) to be included in a list of stunning jellyfish. Like true jellyfish, it can sting, but  if you get close enough, don't hesitate to take pictures because they are not aggressive and the sting will only cause minor irritation to most humans—meaning a beautiful image might be worth the risk!