This is not a sci-fi story but a scientific conclusion made by Chinese geologists after five years of back-breaking study on some fossilized blue-green algae.

Dubbed as a "biological clock", blue-green algae varies its growth rhythm in line with the light changes between days and nights, providing valuable evidence of the movement of time during which they live.

The algae specimen used in this study were dug out from the stratum of Yanshan Mountain of Jixian County, north China's Tianjin Municipality.

Fossilized some 1.3 billion years ago, they have come a long way with floating plates from the equator areas, said Zhu Shixing, a researcher with the Tianjin Geology and Mineral Resources Institute who heads the project.

Calling the find an important contribution to global geoscience research, Zhu said the study report had been published in the Journal of Micropaleontology and aroused extensive attention both home and abroad.

According to Zhu, over 500 stromatolites containing rich blue-green algae have been extracted from a 3,336-meter-thick massif of Yanshan Mountain since 1998.

About 60 have been hand-picked and cut into over 2,000 sections for laboratory tests. On some of these sections, Chinese scientists found more than 1,000 fossilized algae and six to 40 fossilized cells from 300 algae sheathes.

"However, what's more rewarding", Zhu said, "is the clearly revealed growth rhythm of the ancient algae under microscopes."

When nourished by sunlight, the algae grow vertically and have a much more lucid color; when night comes, they grow horizontally and look much dimmer, he said.

To fully record the color contrasts and growth rhythm, Zhu and his teammates have taken 170 micro-photos, which have constituted a valuable material for similar study around the world.

Zhu said the timing function of blue-green algae was originally predicted by scientists in the late 1950s.

However, constrained by the lack of systemic algae fossils, no thorough research was possible until now.

Over the past five years, Zhu and his teammates Huang Xueguang and Xin Houtian have made repeated studies of the specimen and consulted knowledge from many other disciplines such as geomagnetism and climatology.

"This is the first time for humankind to grasp the time rhythm of some 1.3 billion years ago and find solid evidence to prove that the rotation rate of the globe has been slowing down since its establishment some 5 billion years ago," Zhu said.

Jointly funded by the National Natural Scientific Foundation and the Open Lab Funds of the Geomechanics Institute under the Ministry of Land Resources, the project may also speed up the study of the evolution of the Solar System.

(Xinhua News Agency July 8, 2003)