Elon Musk addressed Twitter (TWTR.N) employees for the first time on Thursday, expressing his view that Twitter would need to cut its headcount, but offering few other new details about his $44 billion planned takeover of the social media company.

Musk appeared via video call 10 minutes late to what turned out to be a freewheeling question and answer session moderated by a Twitter executive, in which Musk mused about the existence of aliens and other space civilizations and his view that Twitter should help "civilization and consciousness."

The Tesla chief executive, who is also CEO of rocket company SpaceX, told Twitter staff he wants to raise the service's user numbers from 229 million to at least 1 billion people and said advertising would remain important for the company, despite previously saying he believes Twitter should not serve ads, according to audio of the meeting heard by Reuters.

"I think advertising is very important for Twitter," Musk said. "I'm not against advertising. I would probably talk to the advertisers and say, like, 'hey, let's just make sure the ads are as entertaining as possible.'"

Musk, who was expected to provide assurance to Twitter employees during his first meeting, didn't offer an update on the deal closing.

He reiterated he was still trying to learn more about bot and spam accounts on Twitter, which he called his biggest concern.

In response to a question about whether he expected layoffs, Musk said there needed to be "some rationalization of headcount and expenses."

"Right now, the costs exceed the revenue," he said, adding "anyone who's ... a significant contributor should have nothing to worry about."

Twitter employees took to an internal Slack channel in droves during the session, posting memes and complaining that Musk was not providing useful answers on his vision for the business and employee compensation.

They also demanded on Slack that the moderator press Musk on his views about remote work, as Twitter currently allows employees relatively free reign to work remotely or in the office.

Musk said he believed Twitter staff should lean toward working in an office, but expressed willingness to make some exceptions. The bias should be "strongly towards working in person, but if somebody is exceptional, then remote work can be okay," he said.

The impending takeover of Twitter has been met with widespread skepticism and concern among the San Francisco-based company's employees, some of whom have worried Musk will relax rules on certain content.

The billionaire told Twitter staff he believed users should be allowed to say "pretty outrageous things" on the site as long as the content is not illegal.

Twitter shares were down 1.5% and Tesla shares slumped more than 9% in afternoon trading.

Musk dialed into the call wearing a white shirt and appeared to be sitting in a kitchen, according to a source who watched the call.

When he turned off his video at the end of the Q&A, his avatar appeared to be two hands in the shape of the number 69, an apparent reference to a sex position, the source said.