Storyboard file in Xcode now showing up as an empty folder

I opened my Xcode project this morning and found that the .storyboard file in my project now shows up as a folder named MainStoryboard.storyboard instead of an actual storyboard file. It seems to be the same when I open it in finder and any Time Machine backups, which I find strange because I've had it opened in Xcode more recently than some of the backups.

Is there any way to recover the file or is all hope lost?

This is what I see in the Project Navigator:

storyboard folder

Solution

Turns out someone had opened the project file in a Developer Preview of Xcode. I had to go way back in Time Machine to find a version of the file that would open.