You're gonna have to examine the contents to find out what it is, lol. Use a metal wire (like a coat hanger), or something similar. If it's a green colour, and separates easily, then it's the fiber that turned into a gel. If it's dark brown, and stretches out like bubble-gum, then it's plaque. I've used Holistic Horizons twice, and i never saw the black rubber stuff, just the dark brown stuff i mentioned above.