Item from Futurama by Matt Groening & David X. Cohen
The densest substance in the universe — each pellet weighs as much as 1,000 suns, is produced as Nibblonian fecal matter, and was the primary starship fuel until Mom's monopoly was broken.
Dark matter powers virtually all space travel in the 31st century. It is produced exclusively as Nibblonian excrement, making Nibbler (and his species) walking fuel refineries. Mom cornered the dark matter market by capturing Nibblonians and force-feeding them to mass-produce fuel. Professor Farnsworth accidentally created the crystal that empowered dark matter as fuel while trying to make better harpsichord wax. He later used the Anti-Backwards Crystal to render all dark matter useless, crashing the fuel economy and forcing the development of alternatives like whale oil and 'Nibbler Power' (strapping Nibbler to the engine).
Small, round, dark pellets that appear deceptively lightweight but are unfathomably dense. Each one Nibbler produces weighs as much as a thousand suns, yet he's light enough for humans to pick up — a contradiction the show cheerfully ignores.
Also known as: Dark Matter, Nibblonian Waste