In the Cambrian period, 530 million years ago, life on Earth suddenly became abundant and diverse in the space of 20 million years. Ancient arthropods, brachiopods, Demodex, sponges, and chordates quickly originated during this time period and formed their own animal phyla, which became the origin of this type of animal form in modern times. A flourishing scene of the simultaneous existence of a variety of phyla and animals has been formed.

After the discovery of the biosphere in southern China, as well as the Burgess biota and the Carey biota, which constituted the world's three major shale biotas, the Cambrian explosion of life has become a puzzle that many scholars in the paleontological field are difficult to solve.

Because of the discovery of the Cambrian explosion of life, some of the original evolutionary theories have also begun to be questioned.

It was not until later, when the Ediacara region in south-central Oceania was identified, and the Ediacara fauna, which was first discovered in the Pound sandstone formation, 670 million years ago, was discovered, that the biological evolutionary link between the pre-Paleozoic era of the earth and the Cambrian explosion of life was finally found.

According to today's archaeological excavations, it has been determined that the Ediacaran fauna contains three phyla, nineteen genera, and twenty-four species of lower invertebrates!

These include the phylum Coelenterate, Annelid, and Arthropoda.

It is subdivided into, jellyfish, seven genera and nine species. Hydra class, three genera and three species. Sea gills (corals), three genera and three species. Bowl jellyfish, two genera and two species. Polychaete cycloworm, five species in two genera. Arthropods, two genera and two species.

The morphology and structure of these organisms are extremely primitive, with large, flattened, mostly oval or band-shaped bodies, and smooth organic membranes. This kind of body structure is a kind of attempt in the evolution of life. This type of life in itself does not win by increasing the complexity of the body's internal structures.

Rather, it is to change the external form of the body itself as much as possible. Try to increase the contact area of the body with the outside world by becoming very thin. And use a large area to communicate with the outside world as much as possible, breathe, and take in nutrients. Therefore, paleontologists generally believe that the Ediacaran biota was an attempt by metazoans to occupy the shallow sea on a large scale at the end of the Proterozoic with low atmospheric oxygen content.

Of course, this evolution failed. The organisms on Earth are more suitable for another evolutionary path, that is, to diversify the internal organs of the body, and to gradually diversify the species.

Therefore, the image of this creature made Yun Lei, who had seen the relevant information, deeply remember. In the documentary, the computer-simulated image of the Ediacaran fauna led Yun Lei to think that these creatures were alien creatures.

Therefore, Yun Lei saw that in this lake with a suitable acid-base balance, a suitable temperature, and an area of hundreds of square kilometers, there was still this strange creature with a huge and floating body, shaped like a pancake, but covered with radial round pipes. and a squid-like being, but not the same as a squid, with a pair of antennae, and in detail exactly like a strange creature in the Ediacaran fauna that was reconstructed on the computer.

Yun Lei determined that the biome in this lake was actually those ancient life, the living organisms of the Ediacaran biota more than 600 million years ago! Of course, perhaps the animals in the Ediacaran fauna that still exist after 600 million years should be different from those 600 million years ago, but in any case, these creatures should also be regarded as living fossils.

It is a miracle that it has survived five mass extinctions on the earth in succession and survived to this day.

Of course, this vast lake is not the only Precambrian creatures with strange shapes, such as the Ediacaran fauna. In this lake, there are still a lot of nautilus, strange shrimp that should have been extinct a long time ago. and trilobites, which did not escape the Devonian mass extinction. Wandering in the water, scurrying around.

There are even some strange little fish that are no more than a centimeter long and only the size of a thumb, swimming around in groups. After Yun Lei saw the appearance of this small fish clearly, he was even more surprised, this was actually an early fish living in the Cambrian - Haikou fish!

Of course, there are many fossils found in this lake, fossils that have not been studied for a while, and many strange ancient creatures that have not been seen in the literature.

These creatures, in such a strange environment, very strangely form a delicate cycle and balance of biological chains. As a result, these creatures have not only survived hundreds of millions of years. Moreover, the evolution is unusually slow. Otherwise, the descendants of these ancient relics would have evolved some other lives in this vast underground space that humans could not have imagined at all.

And now, among these ancient creatures underground, except for the nautilus that is now distributed in the seas, the rest of the ancient life has long been extinct.

During the Precambrian period, the Wallenge Ice Age, the Earth experienced about 200 million years of cold.

From 750 million years ago to 580 trillion years ago, the earth had another extremely long and cold ice age. This era is the Wallenge Ice Age. In this era, the land on Earth was completely covered by glaciers. The sea is completely frozen by the cold.

All liquid water exists only under thick ice sheets, supported by the heat provided by volcanoes near the center of the earth, or by magma. And at that time, the ice sheet on Earth was about a kilometer thick!

According to the estimation of geologists, the earth at that time, if you look down from outer space, was completely an ice hockey puck. It's like the Earth's satellites now look at Enceladus and Europa from space.

It seems to be extremely cold and lonely, but maybe life is hidden.

Therefore, between 800 million and 600 million years ago, there are glacial rocks and various glacial deposits. It wasn't until later that the radioactive material in the Earth's interior continued to decay and emit heat, and a large amount of volcanic activity and magma flowed that caused the glaciers to melt.

The earth has just warmed up. According to ancient geologists, the Earth's temperature began to rise from minus 50 degrees Celsius during the Aurora period 800 million years ago. It has risen to the highest temperature of minus 58 degrees Celsius. In 800 million years, it has risen by a full 100 and 8 degrees!

Although there were various glacial periods during this period, the overall temperature on the earth was still generally rising. And this process of rising temperature is exactly in line with the continuous evolution of life on the earth since the Cambrian period for hundreds of millions of years!