Marlenium
From Tardis Wiki, the free Doctor Who reference
Marlenium was a mineral element used by TARDISes. When the Third Doctor discovered that the marlenial elements of his TARDIS were eroding, he journeyed to an unnamed planet to get replacements. After returning from an adventure on that world, he discovered that the marlenium elements had already been repaired by the Time Lords. (COMIC: The Labyrinth)
