Marine Organisms Similar to First Life Forms Found

Scuba divers in the Bahamas have discovered columns of living marine organisms closely resembling the first forms of life that appeared on earth 3 billion years ago, scientists reported Wednesday.

Scientists said the recently discovered columns, called stromatolites, will shed new light on what the planet was like before plants grew on land and fish inhabited the oceans.

“With this one find we have already debunked several theories about the Precambrian period,” which dates from 4,550 to 570 million years ago, said Eugene A. Shinn, a marine geologist at the U.S. Geological Survey Fisher Island Station outside of Miami.

Shinn was one of several marine specialists who reported their findings on the stromatolites in the British science journal Nature.

Stromatolites are created when primitive forms of blue-green algae collect sediment and build deposits shaped roughly like columns, Shinn said.

“They are living and not living,” he said of the masses. “They become rock underneath with a layer of living organisms on top.”

Died Out Slowly

Scientists believe the earth’s oceans were filled with stromatolites from 3 billion to 600 million years ago, dying out slowly as higher forms of life developed and fed on them.

The fossilized remains of ancient stromatolites are scattered over the world, and geologists have studied them to determine what life was like in the Precambrian period.

The only other known living stromatolites were found in Shark Bay, Australia, 25 years ago in water so salty that no other form of marine life survives in it, Shinn said.

“We based a lot of our assumptions of what life was like on that specific find--like the oceans millions of years ago were very saline,” he said. “With this new find we see different conditions and have to rethink our theories.”

The stromatolites described in Nature were discovered in a tidal pass between the Bahamian islands of Lee Stocking and Norman’s Pond Cay about 300 miles southeast of Miami.

Shinn said amateur scuba divers found hundreds of the columns over a 10-acre area in water 25 feet deep. The largest of the stromatolites are seven feet high and four feet thick.

Scientists using sophisticated dating techniques estimated that the columns began forming 480 years ago, he said.