Will saltwater jellyfish Ever Rule the World?

http://kamerontnqw450.aircus.com/a-step-by-step-guide-to-jellyfish-fish-tank-de

A nice size for a 10 gallon tank. Adjustable height and slowly sways with water current. About 3 inches wide and 6-7 in length. Worth the purchase online than in any other major store.