Starseed

Starseeds, also called sailseeds, are a fictional life form in the Known Space science fiction series by Larry Niven. These large (approximately one mile in diameter) "seeds" travel through interstellar space. Nothing is really known about them, other than they seem to migrate from the galactic center to the rim to eject their eggs, and then travel back to the core. Sometimes the eggs are ejected towards other galaxies, but most are left to hatch and migrate themselves to the core.

A starseed is typically spherical, but when it needs to change direction it unfolds itself into a large squarish solar sail with the four corners connected via strands to a small knob. Most of the internal organs are located in a cross-shaped swelling in the sail.

The aliens known as Outsiders follow starseeds for reasons only they know. Pierson's Puppeteers have once claimed to have a technology called "starseed lure" that can attract nearby starseeds to a specific solar system. They have supposedly used a starseed lure to influence the course of human/Kzin warfare by causing an Outsider ship to visit a human colony world, allowing humanity to purchase hyperdrive technology. This technology allowed humanity to decimate the Kzinti in subsequent wars. However, other accounts have it that the outsiders followed an unmanned human starship that traveled between the human colonies (see A Gift From Earth).