black box under back bumper opposite muffler on 2000 Hyundai Tiburon

What is the black box under back bumper% blows black smoke onto back of car

Asked by for the 2000 Hyundai Tiburon
That is the exhaust box some people call it a muffler. It allows burned gas out of the engine through a catalytic converter where the gasses are some what neutralized and exit the rear of the car. It should not have excess oil deposits unless the engine has issues.