Mashable: If you're reading this, it's already too late to post a CoTweet.

Did you use Twitter's fairly new CoTweets feature? If not, it seems you've already missed your chance. And, if you did, say goodbye to it…today.

Twitter is immediately shutting down CoTweets, an experimental feature which allowed two Twitter users to author and publish a tweet in tandem. In a blink-or-you'll-miss-it pop-up announcement(Opens in a new window) hidden away on Twitter's About CoTweets help page, the company announced it would be "sunsetting" the feature starting Tuesday, Jan. 31. 

As of today, users will no longer be able to create CoTweets. According to Twitter, CoTweets will continue to be viewable for another month. After which, CoTweet posts will then be converted into regular tweets. The Twitter user who initiated the CoTweet will be viewed as the sole author of the tweet. The secondary CoTweet author, or the user who was invited to co-author the CoTweet, will be removed from the tweet. The tweet that they co-authored will then be viewable on their page as a retweet of the initial tweet author.

Twitter first launched CoTweets in July 2022, just months before Elon Musk would acquire the company. The company promoted the feature as a way for two Twitter users to make announcements together or to help put a spotlight on another user. These tweets would appear in users' feeds as posted by both authors of the CoTweet. In order to create a tweet, one user would have to initially write the tweet and then send an invitation to another user to appear as the CoTweets co-author before posting the tweet.

This is far from the first time that Twitter has shut down "experimental" features. Most notable, Twitter's version of Instagram Stories, called Fleets, was launched in November 2020. The company shutdown(Opens in a new window) the feature less than a year later in August 2021.

However, under Elon Musk, Twitter has laid off thousands of employees and in turn began to close down products and services that were well beyond the testing phase. Earlier this month, for example, Twitter's newsletter platform, Revue, was shut down. The company acquired(Opens in a new window) Revue in Jan. 2021 and soon integrated features that allowed Twitters users to seamlessly subscribe to Revue newsletters directly on Twitter with a simple click.

As Musk's Twitter makes moves to transform(Opens in a new window) into a payment service, it seems like any Twitter feature that's not core to the platform can be up next on the chopping block. Hopefully, in the future, users will be given a little more of a heads up than a shutdown announcement added to a rarely visited internal help page like Twitter did with CoTweets.