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, in 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 geoscientific research, Zhu said the study report had been published in the Journal of Micropaleontology and aroused extensive attention both at 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.

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.

(China Daily July 8, 2003)