Elon Musk addressed Twitter employees for the first time on Thursday, projecting a need for "rationalisation of headcount" but offering few other new details about his $44 billion 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 "civilisation and consciousness." He told Twitter staff he wants to raise the service's user numbers to at least a 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.'" 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.

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.