What is a muffler bearing ?

What have you run into that makes reference to a muffler bearing? The usual muffler of an auto is an insert in the exhaust system that lessens the exhaust roar of the engine. It isn't supposed to have any rotating parts that I know of, and therefore doesn't have bearings. There are exhaust TURBINES which are installed to provide power to superchargers, and they must have bearings for the rotating wheel(s).  more