1.   By analogy, he explained, the shingles on the side of his house are covered with living microbes.

2.   Desert varnish is a thin surface film that is generally believed to be produced by living microbes.

3.   For example, there are odd cave formations that have long been known by cavers but are only now being identified as products of living microbes.

4.   It may well be that most of them are produced by living microbes, he said.

5.   Levin has maintained ever since that mission that his experiment showed clear evidence that living microbes exist on Mars today.

6.   On the contrary, she said, she found teardrop-shaped magnetite crystals that are thought to occur only in living microbes.