About half of the relatively small portion of the universe that is not dark matter or energy is in fact a mixture of gases that may connect galaxies in a kind of loose cosmic web, according to new research illuminating vast areas that were previously unknown.

Until now, this sizable chunk of “baryonic matter,” which makes up 5% of the universe, had been unaccounted for. Researchers from institutions in Spain and the Argonne National Laboratory in Illinois detailed their findings in a study published March 25 in Monthly Notices of the Royal Astronomical Society.

While the other 95% of the universe is made up of dark matter and dark energy, baryonic matter comprises stars, planets, galaxies and everything they contain, including living things. Astronomers knew it was there, but didn’t know if it was more stars, planets or anything else that wasn’t dark matter or energy.