As well as the joy that comes with swimming, there can also be some dirty risks.

Fossil evidence of how the earliest life on Earth came to be is hard to come by. But scientists have come up with a few theories based on the microbes, viruses and prions existing today.

"Think of it as Earth's skin," says Jon Chorover of the critical zone. "It's sometimes termed the zone where rock meets life."

Prochlorococcus, the world’s most abundant photosynthetic organism, reveals a gene-transfer mechanism that may be key to its abundance and diversity.

Harnessing these protective molecules may offer a new way to treat the disease, which spreads through contaminated water.

Up to one-third of the carbon consumed by Prochlorococcus may come from sources other than photosynthesis.

Researchers simulated the conditions hypothetical lifeforms would have encountered on Mars 4 billion years ago.

The walls of your house could someday be built with living bacteria. Synthetic biologists are engineering microbes into living materials that are cheap and sustainable.