Stones that can "breathe": They are as good at producing oxygen as plants

May is the season with the most suitable temperature, lush flowers and fragrant grass. It is a good time for outdoor activities. It is very pleasant to enjoy the fresh air and feel the charm of nature. Many natural attractions also use "natural oxygen bar" as a major selling point, such as our Stone Forest.

The oxygen we breathe comes partly from photosynthesis of plants. On Earth, there is another type of rock that produces oxygen: stromatolites.

Stromatolites are the dual product of biological and geological actions. Their formation is mainly due to the periodic life activities of prokaryotic algae (such as cyanobacteria and other microorganisms). These organisms are so small that they can only be observed under a microscope, but they are numerous. They continuously secrete sticky substances to capture soil and sand in the water and cement them together. Since these microorganisms live in shallow sea areas with slow currents, with the passage of time and their repeated activities from generation to generation, the cemented soil and sand grow and solidify layer by layer in fixed positions, eventually forming bulges on the surface, and the whole looks like a cauliflower or a mushroom. Such rocks are vividly called stromatolites.

There is not only one kind of microorganism on the same stromatolite, but a community of organisms composed of multiple microorganisms, also called microbial mats, because they are entangled with each other and interwoven into mats that cover the rocks. In a few parts of the world today, such as Shark Bay in Australia, the shallow sea of ​​the Bahamas, and the Salt Lake in Utah, USA, you can still see such dull rocks. If you look closely, you will find that the underwater parts of these rocks are constantly spitting small bubbles, just like breathing. This breathing is the process by which these microorganisms obtain nutrients through photosynthesis, and oxygen is a byproduct of this process.

Although stromatolites are now rare, they were once extremely abundant in the distant past, with the oldest fossil evidence being 3.5 billion years old. What they do has never changed, but they continue to cause huge changes to the Earth's environment.

The large amount of oxygen they released changed the composition of the Earth's atmosphere, gradually transforming the early Earth's reducing atmosphere into an oxidizing atmosphere. However, as the saying goes, one man's meat is another man's poison. Free air is not sweet to everyone. For most anaerobic organisms at that time, it was a fatal disaster. Some of the survivors took refuge in the large chimneys in the sea - hydrothermal vents, while more made changes: becoming multicellular organisms, using adhesive membranes to isolate oxygen to protect themselves, and trying to coexist with oxygen... These changes laid the foundation for the later emergence of more complex and diverse life forms with more complex forms and structures.

The unintentional actions of these microorganisms on the stromatolites can bring about earth-shaking changes in the appearance of our planet. As conscious beings with the ability to transform the natural environment, we should learn from history and seriously consider the impact our activities will have on the future of the Earth.