The bacteria that digest plant material in the rumen of cows are an example of

A cow eats plant material like hay and grass that is full of cellulose. Cellulose is very hard to digest, so the cow relies on bacteria and other organisms that live inside them to break down the cellulose into a form from which they can extract nutrients. The ruminant stomach is vastly different from your own digestive system. Without cellulose-digesting bacteria, cows wouldn't be.