If Arnold Schwarzenegger had a pet cow, I can almost guarantee it would be a Belgian Blue. These cows are incredibly muscled and have very little fat. Many people think of this breed as evolution in action—because a mutation in its DNA has brought about a supposed improvement.
But if microbes really did turn into Belgian Blue cows—which is what evolution teaches—this would require the addition of lots of new DNA information to turn the relatively simple genome of a bacteria into the vastly more complicated genome of a cow.
However, in the case of Belgian Blue cows, we see the opposite, because no new information has been added. In fact, a mutation has corrupted the myostatin gene, which normally stops muscles growing too big—so information has been lost. The cows have lost control over muscle growth. So Belgian Blue cows have devolved, not evolved!