Question on rear interior quarter panels

[jawn101]

Clint and I had the interiors of our cars out today to work on installing dynamat and ran into a question neither of us had an answer to. What are these C-shaped clips for on the interior quarter panels? There doesn't seem to be *anything* in either of our cars for them to hang on. Anyone know what they're for?

Pic below...

[jmettee]

My car was the same. I think they were intended for plastic fir tree fasteners or similar, but were never utilized.