Bazoolium
From Tardis Wiki, the free Doctor Who reference
Bazulium was a substance which could turn hot when it was going to be a sunny day, and cold when it was going to rain.
Little trinkets were fashioned out of Bazulium. At least one was once sold at a trading bazaar based on an asteroid and bought by Rose Tyler as a gift for her mother. (DW: Army of Ghosts)
