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Well, does it sound like it's leaking anywhere? If so, the pipe could have snapped and is vibrating against the piece it broke from.

If nit, it could be a loose heat shield or a broken hanger. Take a look and check them, as a broke hanger will cause the pipe to sag and could drag the pavement, break another hanger, or even snap the pipe.

Hi probability its the heat shield on the catalytic converter.

It looks kinda like a mini muffler towards the front of the exhaust under the car.

If the car is rather old and you are in a cooler/colder climate you could just remove the loose section and carry on, but if you are in a tropical type environment then you might want to replace it else the floor of the vehicle will be getting rather warm during long hours of usage.

There are also heat shields on the pipe sections of the exhaust on some cars and same around the muffler but generally its the catalytic converter shields that go first. later the shields towards the engine from the converter because there are the sections that stay warm the longest thereby favoring rusting rates.

If it rattles while idling, crawl under there and try to locate it.

You might hear rattling inside the muffler. When a catalytic converter disintegrates, it can shed pieces down the exhaust which end up stuck in the muffler. If that has happened, both the cat and the muffler need to be replaced.

I had a muffler rattling like this on a different car which was a few years older than yours. When it finally split open a year ago (forcing me to finally replace it) I found catalyst parts inside.