Jellyfish are beautiful- I agree. I got stung once. That wasn't so nice. Nothing serious but, kind of scary- I was snorkling with my Dad. We started to spot one or two and then, they just seemed to be all around us. They weren't the really venomous type.
I haven't seen that many in aquariums. Only Moon Jellyfish I think. I'd love to have an octopus but I think they're pretty specialist and they don't live that long in captivity. I love sea creatures.