The sink got clogged up the other day. Pictured is what I pulled out of the drain. What the heck is it??? Normally when I pull stuff out of the drain, it's mostly decomposing hair. This time it was mostly this black stuff. Looks like tar, but breaks up into little chunks when thrown in the toilet. For what it's worth, I saw what looked like the same stuff in a vent pipe on our roof a few weeks back when I was working on it.
For Part I, go to my wife's blog, this entry:
What is this Part I