No billionaire left behind.

After Mark Zuckerberg, Peter Thiel and other Silicon Valley notables plunked down capital in a $40 million growth round for San Francisco-based artificial intelligence startup Vicarious, a few more billionaires showed up.

Amazon CEO Jeff Bezos, Yahoo co-founder Jerry Yang, Skype co-founder Janus Friis and Salesforce CEO Marc Benioff all showed up to give Vicarious an additional shot of capital in its Series B round.

The company isn’t disclosing how much extra funding they’re getting from these four, but it’s definitely not “angel-sized,” co-founder D. Scott Phoenix tells us. (I also can’t really think of a time when this many CEOs and founders of this stature got together to personally fund a company.)

Vicarious is working on the next generation of artificial intelligence technology. Phoenix said that the AI field is still centered around convolutional neural network technology that was developed back in the 1980s.

But by more closely mimicking how the brain works, Phoenix and his neuroscientist co-founder Dileep George say that they’ve been able to make breakthroughs in performance and speed. Last fall, they showed off a way to solve Captcha queries.

They’re hoping that Vicarious’ technology will eventually lead to the world’s first intelligent machines.

The company is still incredibly small at this point, with more than $56 million raised for a headcount of 10 employees (which sounds crazy). But Phoenix said they’re planning to ramp up headcount dramatically.

Vicarious’s other investors include Joe Lonsdale’s Formation 8; Vinod Khosla; Ashton Kutcher; Aydin Senkut’s Felicis Ventures; Garry Tan and Alexis Ohanian’s Initialized Capital; Bryan Johnson of Braintree; Box.com CEO Aaron Levie; Sam Altman; Open Field Capital; Zarco Investment Group; and Metaplanet Holdings.