The co-founder of virtual reality company Oculus said on Monday he was leaving the firm, which is now owned by Facebook, continuing a string of high-profile executives to part ways with the social network and its subsidiaries Instagram and WhatsApp.

Brendan Iribe wrote on Twitter that he was “moving on to the next chapter” six years after he launched Oculus and its Rift headset with a group of co-founders.

“What a ride! We made science fiction into reality and inspired a new industry in the process. Oculus was only possible because of such an extraordinary team and community. Thank you!” Iribe tweeted.

Iribe, who stepped down as Oculus CEO in 2016 to focus on product development, did not give a reason for leaving and could not immediately be reached for comment.

What a ride! We made science fiction into reality and inspired a new industry in the process. Oculus was only possible because of such an extraordinary team and community. Thank you! Now, six years after we launched Oculus and Rift, I'm moving on to the next chapter! — Brendan Iribe (@brendaniribe) October 22, 2018

Facebook said in a statement that Iribe “pushed VR far beyond the boundaries of what people thought possible and it's because of his vision that we're all here working on VR today. We're thankful for his leadership, his dedication to building the impossible, and he'll be missed.”

Facebook paid $3 billion in 2014 to acquire Oculus and retain its employees, entering the computer hardware business for the first time in a significant way and betting that there would one day be a large market for virtual reality.

Another Oculus co-founder, Palmer Luckey, left in 2017.

Instagram co-founders Kevin Systrom and Mike Krieger left Facebook last month. They had clashed with Facebook CEO Mark Zuckerberg over a range of issues, sources have said.

Systrom said this month, “No one ever leaves a job because everything's awesome.”

WhatsApp’s co-founders launched a public feud with Facebook’s management after they left beginning in September 2017, as one tweeted “#deletefacebook” and a Facebook executive fired back calling the criticism “low-class.”

Facebook bought WhatsApp for $22 billion in 2014 and Instagram for $1 billion in 2012.

Facebook itself has lost several executives in the past year, including chief marketing officer Gary Briggs, vice president of partnerships Dan Rose, communications chief Elliot Schrage, chief security officer Alex Stamos and general counsel Colin Stretch.