The earliest stars in the universe may have been cool expanses of helium and hydrogen, thick with dark matter and spitting with antimatter. There even may be a few still around.

What some astrophysicists are calling 'dark stars' would have been dominated by dark matter and could have existed for millennia in the early universe, when dark matter was far more concentrated than today.

Some dark stars might have even survived to the present day.

What's more, these theoretical dark matter stars may be the secret behind the giant black holes called quasars, which appear to have come into existence before galaxies had a chance to create them.

That timing has never made much sense before.

The dark matter in these weird stars would have to be some kind of heavy subatomic particle that only interacts with normal matter by tugging on it with its gravity.