The world's most expensive substance goes for $62 trillion for a single gram - and you can't even buy it.
It goes that the rarest and most valuable materials don't even come close to that of gold or diamonds.
And even if you had that kind of money, you wouldn’t be able to get your hands on it.
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Why? Because there might not even be a full gram of it anywhere in the entire universe.
It's called antimatter and it is the mirror image of the atoms and particles that make up the universe around us.
Antimatter can't be mined or produced in bulk.
Instead, the ultra-rare substance must be assembled atom by atom in a process that requires some of the most advanced technology on Earth.
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It could take a billion years to gather one-tenth of a gram.
Although scientists have put their heads together to create antimatter for study, it still disappears almost instantly, making it incredibly expensive to do so.
Antimatter is basically matter in reverse. For every proton, electron and neutron in the universe, there’s an antiproton, positron, and antineutron with the opposite electrical charge.
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According to the experts, these antiparticles can be assembled into antimolecules and in theory into entire antimatter planets and galaxies which wouldn't look all that different to ours.
In 1999, NASA scientist Harold Gerrish estimated the cost of antimatter at $62.5 trillion per gram - or $1.75 quadrillion per ounce. This took into account the energy involved and the estimated production capacity.
But with today’s engineering obstacles, experts believe the true price is likely even higher.
"We make such minute quantities that even if you were to destroy all the antimatter that we're making in the course of a year, it wouldn't be even enough to boil a cup of tea," said Professor Michael Doser, a particle physicist at CERN (European Organization for Nuclear Research).
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"One 100th of a nanogram [of antimatter] costs as much as one kilogram of gold."
That would make the price for a gram approximately $5.24 quadrillion (£4.16 quadrillion).
Believe it or not, antimatter is being created all the time - inside us and around us.
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However, because these particles are quickly eradicated by the surrounding matter, it's basically useless for study.
Instead, scientists have to force it into existence: by concentrating so much energy at a single point that it actually becomes matter.
At CERN, a team of scientists use particle accelerators to speed up streams of protons and slam them into iridium blocks.
About once in every million collisions, a tiny antimatter particle is created alongside a regular matter twin.
The potential of antimatter is huge, however. Because of its high energy density, it could likely revolutionise space travel at some point in the future - if we can keep it around for long enough to store.