Could dark matter — the elusive substance that composes most of the material universe — be made of black holes? Some astronomers are beginning to think this tantalizing possibility is more and more likely. Alexander Kashlinsky, an astronomer at the NASA Goddard Space Flight Center in Maryland, thinks that black holes that formed soon after the Big Bang can perfectly explain the observations of gravitational waves, or ripples in space-time, made by the Laser Interferometer Gravitational-Wave Observatory (LIGO) last year, as well as previous observations of the early universe. If Kashlinsky is correct, then dark matter might be composed of these primordial black holes, all galaxies might be embedded ... Read more at the link below/ http://www.space.com/33122-dark-matter-black-hole-connection.html This is another interesting article. Black Holes forming right after the Big Bang would suggest to me that the first suns of the Universe consumed their fuel rather quickly and then collapsed into Black Holes and were then blown apart by the rapidly advancing Big Bang explosion or the Universe "sucking motion" of the expanding Universe.
No, primordial black holes weren't formed by stellar collapse, as the article explains further down (although its analogy to "sound waves" isn't great). Rather, they emerged spontaneously out of the hyperdense matter and energy that existed in the split-seconds after the Big Bang. They could be any size down to microscopic, although the small ones would've evaporated long ago, assuming Hawking is right about his namesake radiation.
I think I'd rather take the negative energy barrier to being surrounded by all these things. Just like the universe to prevent intergalactic travel with potholes.