So I found this random, out of place wire when I was detailing the interior of my MB

[EdmondsAve]

I was cleaning out the old 300D, getting ready to move to Little Rock to finish my bachelors and house-sit for the next 6 months to a year, and while I was vacuuming the back seat on the passenger side, I find this cable hanging out of the plastic cover in between the front and rear doors. At first, I thought the idiot who used to own this car had left some co-ax cable (like used for cable on your television) under the seat when he was jerry-rigging something that broke (ive found a bit of that while trying to restore this pile), but upon closer examination, I found that it wasn't co-ax cable. The question is, what is it exactly? its thick, like co-ax, and has a simmilar looking end (its obviously the male end to watever its connected to, as it has a metal, cylindrical head with a thicker-than-co-ax metal prong at the end. I couldnt find where it hooked up, however, so I was wondering if you all could guide me. My initial thought was that it went to my stereo somehow, because the antenna doesnt work (and honestly, it looks like it would plug into the back of the head unit if the metal wasnt totally encompassing the prong), but I'm beginning to think that maybe it was a piece to a previously installed CD Changer, but I really cant tell. it runs all the way towards the trunk under the "kickpanels" along the rear passenger door.

Let me know if you can figure out what it is.