After three days of cringing, I volunteered to clean the shelves, provided people removed their decaying detritus in a timely fashion.
Among other curdled disgustingness, this is what I found:
Okay, in deference to the truth, this picture is from the Internet and the blackened object that I found went immediately into the garbage (after I showed it to the co-workers, of course.) It was inside what I believe to be a former employe's lunch bag. She's been gone since 2009.
I need to go boil my hands now. And then this keyboard.