iPod headphones covered in oily residue
Hi! I have used my iPod for two years and at some point I got a second set of headphones, so I set the original ones aside in a box. The box was not exposed to the light or to extreme temperatures. I have not taken the headphones out of the box for ca 2-3 months. Today I found oily reisdue on the headphones, the cable surface is covered with it, there is some on the speakers. The smell is really bad. There are also a few small cut-like holes that haven't been there before.
What happened and are the headphones safe to use?
MacBook Pro, Mac OS X (10.7.5)