Twitter has quietly killed off a feature that allowed users to publish co-authored tweets. The company enabled CoTweets on "select" accounts last July in the US, Canada and Korea, but the feature never made it beyond the experimental stage. As of today, you'll no longer be able to post CoTweets.
"We’re sad to say that the current experiment is coming to an end," Twitter wrote on an updated support page. "Already existing CoTweets will be viewable for one more month at which point they will revert to retweets."
If you invited someone to CoTweet with you, that tweet will remain on your account, according to Mashable. For those who were invited to co-author a tweet, CoTweets will soon appear as retweets from the other person's account. All clear on that? Swell.