Q:  What is Earth’s only non-indigenous life form?

A:  Fungi…sorry, sort of a trick question. Of course, the physical building blocks of all life forms originated on the planet Earth, but, their current forms have been molded by Fungi.  The original fungus originated in an unknown damp sector of the universe and impregnated the earth with a single, stray spore via meteorite.  Before the introduction of this lone wolf shiitake, the world was a tired pile of burping algae content with eating and reproducing under the sun.  Within the turn of the century, chewing gum, rubbers and parasols were available for purchase in every major city!