What In The World Is This Nastiness?

Here's a hint - it is found somewhere in our building. I ran across this site earlier today and was so disgusted, yet attracted, that I couldn't leave it alone. I want to know what you think it is.

Obviously I know the answer, but I can think of a few things that it also looks like. So before you watch the video and get the answer, leave a comment with your guess. Don't cheat!

Just so you know, I hardly ever use this particular water bottle. It is on the "other side" of our building, and the one in the kitchen is closer to me. Believe me, I would have taken care of this monstrosity if I had to look at it every day. Just like when I shot that coffee mess video, I have to ask how someone can see that and not do something about it - this mess obviously didn't happen in the course of one or two days. That's some serious growth!