Bombastium
Bombastium is a fictional chemical element. Its Atomic number and atomic symbol are unknown. Bombastium is stated to be the rarest element in the world. Even though it is very coveted, its usage potential is not entirely known. One characteristic is that it tastes different every time you try it, and scientists eventually discovered that one atom of bombastium dropped into a barrel of water becomes one barrel of ice cream - a different flavor of ice cream each time. To avoid evaporation, bombastium must be kept frozen.
The last piece of bombastium known to exist (about the size of a soccer ball) was acquired by Scrooge McDuck of Duckburg in 1957, but at that time it was also heavily sought after by the hostile nation of Brutopia. Brutopia's military spending budget that year amounted to one trillion dollars plus all the kitchen sinks of its happy people. Scrooge McDuck therefore had to pay one trillion dollars plus six kitchen sinks to win the auction.
The element was also used for the 5-part DuckTales episode Time is Money, which introduced Bubba the Caveduck. In this cartoon episode, bombastium is the fuel for one of Gyro Gearloose's inventions, a time traveling helicopter named the Millennium Shortcut. The bombastium itself must be kept frozen in order for it to be usable as fuel (a small freezer is equipped on board the Shortcut for this purpose). Otherwise, the Shortcut could not travel through time.
One of the treasures that can be obtained in the computer game DuckTales: The Quest for Gold is bombastium. Unlike the other treasures, bombastium is worth more than just money, as Gyro Gearloose can use it to build a matter transporter which takes away the risk of flying from place to place while having the possible downside of sending the player to a location they hadn't intended to go.
Read more about this topic: Duck Universe