Billionaire inventor Elon Musk is the one who appeared to be nervous when he took elite Marines by surprise on Friday.

The tech entrepreneur who owns the Telsa electric car company and is trying to pioneer privately funded space travel was the undisclosed guest of honor at the battalion ball for the 1st Marine Raiders of Camp Pendleton, California, Business Insider reported. About 400 people, including World War II vets and Gold Star family members, were in attendance, a Marine Raider told the outlet.

Musk said, “‘I wanted to come and speak to this group’ and I get the chills even saying it, ‘because whenever there’s danger in the world, you all are the first to go and die,’” according to Joe Musselman, CEO of The Honor Foundation.

“And the whole room, you could‘ve heard a pin drop,” Musselman said. “When he said that, the way he said it, it wasn‘t prepared, there was no script. He was genuinely looking up in the air to find the words to say ‘Thank you for doing this, for serving our country.’”

Musk shared some lessons from Silicon Valley, and also ate the first piece of birthday cake ― reportedly served from the commanding officer’s sword.

“That‘s intimidating for any person,” Musselman told Business Insider. “A Marine Raider just served [Musk] a piece of cake off his sword.”

Andrea Scott is managing editor of Marine Corps Times. On Twitter: @_andreascott.