These Magic Urns are not like the ones in FFVI or FFVII. The ones in FFVI cast Life and Cure on your party then run away, leaving behind some Magic Points. The ones in FFVII require and Elixir in return for large amounts of EXP and AP. The ones in FFX are completely different. They do not require you to give them any items, so I advise you stop doing so right away. All you need to do is attack a single eye. If it is the right one then you will be rewarded with an item. If you are then you are free to attack another eye. If, however, you attack the wrong eye the little alien inside the pot will raise it's antenna, jump out of the pot and explode, usually reducing the party to critical health. Therefore it is recommended that you grab a couple of items and Flee. They cannot be defeated.