Scientists studying submerged sinkholes in the Great Lakes off
the coast of northern Michigan have stumbled onto something they
never expected to find: life-forms akin to those found in some
of Earth's most extreme environments. As groundwater leaks
upward into Lake Huron, it redissolves an ancient seabed and
creates a salty underwater environment that is supporting mats
of primitive purple microbes -- cousins to bacteria that live in
deep-sea hydrothermal vents and ice-locked Antarctic lakes. The
discovery in Huron's Thunder Bay underscores how little is known
about the forms that life takes on Earth, or even where they
might be found. In this case, scientists wonder if the microbes
may be truly primordial. Researchers found that the purple
bacteria can photosynthesize as easily in sulfur-rich water as
they can in freshwater, an ability suited to the dim and sulfur-
rich conditions of shallow, primeval seas that existed billions
of years ago. "We see this as a peek into the ancient world,"
said research ecolo