Instagram seems to always be tumblr hot sex videotesting a new feature or two, and this week, Storylines is on the docket.

App researcher Alessandro Paluzzi posted a screenshot on Threads earlier this month that Instagram was working on Storylines, but posted confirmation of the test on Sunday, along with a screenshot that shows how the feature works.

"Link stories to make a storyline," Paluzzi's screenshot of the feature reads. "Friends can link their story to yours. Followers you follow back can link a new related story to your story."

View on Threads

From this description, it looks like Storylines are basically collaborative Stories built by you and your friends in the app, similar to a more collaborative version of "Add Yours."

"The storyline grows as friends add to it," the screenshot of the feature continues. "As people join, followers they follow back can also add. Change who can join or turn storylines off in settings."

If, for example, you're celebrating a friend's birthday, you can add some pictures to your story, and your friends can add their own birthday content, building an even bigger Story together on the app.

"Stories in a storyline show up together," the feature reads. "Followers can see your story. Anyone can see you're in the storyline."

If you love the idea, don't get too excited — a Meta spokesperson told Mashable that "this is an internal prototype and not testing publicly." So it's not clear when, or if, this feature will ever be widely available.

This article has been updated to include a comment from Meta.