Panspermia

Panspermia refers to the hypothesis that life exists throughout the Universe, distributed by meteoroids, asteroids and other spatial bodies.

Examples

 * In Prey earth was seeded by an alien races known as the Keepers to be harvested at a later time.
 * In Spore this is how life makes its way from world to world, the played of the game begins as life from within an meteorite.
 * In Star Trek the primordial oceans of several worlds throughout the Milky Way Galaxy where seeded by the Ancient Humanoid.