The top and bottom layers are oil and water, respectively. The middle layer is the interesting one. It might be an oil-and-water emulsion (emulsion b/c the oil and water were mixed so thoroughly they did not separate like the non-emulsified oil and water layers did), which looks like it has some soot, burnt oil, or exhaust gas mixed in to give it that dark color. The good news: OCC is definitely catching oil and keeping it out of the combustion chamber.
I have some questions about what this liquid looked like when you removed it from the OCC: (1) Was the catch can/liquid still at engine operating temperature, or had it cooled nearly to the local temp? (2) If your catch can is clear, was the liquid layered like this, or was it all mixed together and then it separated after you removed it from the OCC? (3) Did you, or will you, send it to a lab for analysis? Finally, how many miles since the last oil change?
I asked question 3 b/c there seems to be a lot of "garbage" in there, and I'm wondering what it is. It could tell us a lot about what's going on in the engine.