The two richest men in the world appear to have teamed up against a common adversary.

It's rare to see Elon Musk and Jeff Bezos agree on things.

The former is the richest man in the world with an estimated fortune of $209 billion as of June 14, according to Bloomberg Billionaire Index. 

The second is the second richest man on the planet. His fortune is estimated at $126 billion. 

Musk and Bezos clash in particular in the conquest of space via their respective companies SpaceX and Blue Origin.