Facebook's secretive Building 8 hardware lab is Engsub Archiveslosing its boss.

Regina Dugan, who left Google's Advanced Technology and Projects group to lead Building 8, announced that she will be leaving the social network at the beginning of 2018 to "focus on building and leading a new endeavor."

The former DARPA chief didn't say what she would be doing post-Facebook, but said the move was a "difficult decision" for her. At Building 8, which she joined in 2016, she lead some of Facebook's most experimental hardware efforts, including its "brain computer interface project."

In a separate statement obtained by Recode, Dugan said "the timing feels right to step away," from the group she joined a year and a half ago.

"There is a tidal shift going on in Silicon Valley, and those of us in this industry have greater responsibilities than ever before,” she said. “The timing feels right to step away and be purposeful about what's next, thoughtful about new ways to contribute in times of disruption.”

Her sudden departure -- and statements surrounding it -- have also raised questions about what internal factors may have led to her decision to leave.

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It's not clear who will oversee Building 8 directly, but Dugan's departure comes just weeks afterlongtime Facebook exec Andrew "Boz" Bosworth was moved from running Facebook's ads business to overseeing all its hardware efforts, including virtual reality and Building 8.