What is microbial matter? Other than a geologist, this would probably result in a bunch of confused faces if mentioned to your average person. Of course there would be the connection to the microscopic arena, but further than that might take a little more thinking.
So for the confused, sedimentary rocks that contain microbial matter has been formed by deposition of sediments and then it is altered by bacterial matter. And there are several types of these microbial matter that comes to mind which I will get into later