A great capture - the colors and textures are really interesting. The composition doesn't quite highlight the words "ivory black" so it doesn't quite ring clearly for the challenge.
Good idea, but off the mark in two ways. "Ivory Black" is an oxymoron, not a pair of opposites. The Ivory Black is not in focus. Your focus is just behind it, shifting the center of interest off your intended focus.
I gues that oposites here are the colors itself. As a contrasting black and green. The subject to me is not clearly defined, but a second look made me saw.
Interesting subject. Decent composition. I think your title is a bit of a stretch since the Ivory Black tube isn't the first thing the eye is drawn to. Mine keep gravitating to the Sap Green in the foreground.