If that is on the bellhousing, it is just a dust plug. I assume by the last picture that it is on the back side of the engine, between the engine and the transmission? If so, you have something else leaking that is coming out of that area. The most likely would be the rear main seal, a seal that goes at the back of the crank in front of the flywheel. If it is engine oil that is leaking, that's most likely it. If you have tranny fluid, it's coming from the front of the transmission. Do you have a manual or auto tranny?