The interface was first discovered by app researcher Jane Manchun Wong who found the interface in the Android version of the Facebook app.
Currently, Facebook Stories and the News Feed exist alongside one another as distinct interfaces in the core Facebook app.
You can scroll down to see the News Feed or tap one of the cards tiled along the top of the app to start scrolling through your stories.
In this new design, Stories and News Feed posts — including text posts, pictures, videos, and sponsored posts — appear as part of the same interface.
Responding to the discovery, a spokesperson from Facebook said, “We are not currently testing this publicly.” It’s currently unclear whether the interface discovered today will make it to public release.
Facebook briefly experimented with a horizontal interface for Instagram’s feed at the end of last year that was hugely unpopular with users.
The service initially claimed that the new interface was meant as “ a small test ,” but it later called it “a bug” in a statement.
Update April 15th, 12:06PM ET: Added statement from Facebook.