FRAGMENT FROM NATURE contemplates a part of biological dark matter. Dark matter in biology includes the large portion of the genome of unknown function (“junk DNA”) which was of ancient retroviral origin; the second dark matter in biology, and the subject of this essay, is that of the enormous amount of external genetic material that we know nothing about, supposedly viral or bacteriophage in origin. We do not need to explore other planets to find new frontiers. Our own is full of uncharted territory.