Galactic plankton

Space Graphics by Mads Dam

Most types of galactic plankton drift silently in interstallar space.
It spends 99,99% of its lifetime in a dormant state, dreaming of light.
Awakes only when a nearby star blossoms into a nova, drowning space with light.
Within seconds plankton multiplies into millions of copies devouring
most of the photons that would otherwise have flooded the skies.
In short, thanks to plankton the nightsky remains black...