Astronomers tallying up all the normal matter—stars, galaxies and gas—in the universe today have come up embarrassingly short of the total matter produced in the Big Bang 13.6 billion years ago. In fact, more than half of normal matter—half of the 15% of the universe's matter that is not dark matter—cannot be accounted for in the glowing stars and gas we see.
One of the ions of hydrogen is a proton, but there’s also a proton and one or two neutrons for deuterium and tritium, and anion versions of the 3 isotopes where they absorb an extra electron, mostly within stars.