A infinitesimal fowl that says "Quark! Quark!"
Quantum Duck is a strange visitor to our world. His home planet is an electron orbiting an Oxygen atom. His is a technologically advanced culture; they even have rudimentary time travel devices. They also have a Quantum Substring Scalar Mass Exchanger. This simple device allows Quantum Duck to change size at will (battery power willing).
Unfortunately Quantum Duck's home was the unfortunate subject of human experiments. The nucleus of Quantum Duck's Atom - somewhat analogous to our earth's sun - has been struck by a high energy beam in a linear accelerator. Quantum Duck was sent back in time by a small group of renegade scientists to convince a young human to avoid firing his particle beam in the first place. Sadly, Quantum Duck did not manage to do this. Now his only hope is to learn enough about macro-particle physics to build a time machine in our world, then use it to try once again to fulfill his mission.