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An investigation involving the Consejo Superior de Investigaciones Científicas (CSIC) for the first time explains the process of formation of some crystalline materials called biomorphic silica which, despite being made of inorganic minerals, imitate round and gentle life spirals, cardioid, blood cells, septate filaments ...

The study, published in Science, has important implications because it shows that the curved shapes and complex are not unique to biology, the morphology can not be used as a conclusive finding primitive life.

"Until recently, smooth surfaces and curves were synonymous with biological activity," says Juan Manuel García Ruiz, Instituto Andaluz de Ciencias de la Tierra (CSIC Joint Center and the University of Granada). "In this paper we emphasize the idea already present in our previous articles, there is no difference between the symmetry of the inorganic world and the symmetry of the world of life, a notion that we have instilled from the classical Greeks, "he continues. "The morphologies presented in this article as well emulate the ways of life that is obviously an example of the falsity of this concept," concludes the researcher, one of the two signatories of the article together with Spaniards Emilio Melero García, also of the Institute Andaluz de Ciencias de la Tierra.

This implies that the soft, round shapes are not necessarily synonymous with life, so that morphology can not be invoked as an unambiguous criterion for identifying primitive life when looking for fossils in the oldest rocks on earth or in other planets. "The investigator goes even further by stating that" given the similarity between these structures and the most primitive organisms, nor the morphology or chemical composition can be used as a reliable criterion for the study of primitive life on Earth. "

This conclusion was derived from a previous article of researchers - also published in Science, on the plausibility of biomorphic geochemistry of carbonate and silica and their possible formation in the waters of the primitive Earth. This opened a great debate among scientists about the reliability of data on the appearance of life on Earth, what kind of life was the first and the currently accepted criteria for detecting life on other planets.

The work also provides important keys to understanding the processes of biomineralization, which allow living things to create a huge number of functional structures and tissues from crystalline minerals, such as bones, teeth, shells of mollusks, bones of sea urchins, coral walls and exoskeletons of insects.

Despite the fact that living beings take 600 million years using mineral crystal to create these structures, how they do it is still a mystery. In nature, these minerals, mainly carbonates, phosphates and sulphates of calcium, strontium and barium-take different forms, usually solid crystals with sharp edges and flat faces and well defined, never curved or complex forms.

How do living organisms change then this symmetry to the form of, say, the car of a snail? So the biomorphic silica are "valuable" laboratory models to advance the understanding of mineralization processes. "Since, nowadays, we do not know what a snail is able to create its shell, or how we create our bones it is important to understand how these materials laboratory is capable of generating complex and beautiful with continuous curvature, "concludes Garcia Ruiz.

The biomorphic carbonate and silica are laboratory materials, nanocrystalline compounds obtained synthetically and restrained by gently curved surfaces. Although already known, their formation mechanism was a mystery until now.

With video microscopy, the researchers were able to observe in detail the growth of these structures. In the videos it appears that the compound grows in the form of films whose edges are rizando while growing lengthwise. When two loops that propagate in opposite directions are close to each other (while the flat part of the film continues to grow-out), the blade is curved in the same direction of rotation of the border and, according to the speed of growth, results in different ways. One of the most striking are those who have observed or helicoidal shells of various types that grow to about 30 microns per hour and consist of millions of barium carbonate crystals in the size of a few tens of nanometers.

From this work of observation, the researchers propose a theory about the formation of these structures. Essentially relies on the presence during the entire process of growth, a high concentration of impurities, in this case of silica, in the carbonate mineral. Andalusia crystallize, pH oscillations occur on the face of the crystal growth, causing the precipitation of crystals alternating amorphous silica and carbonate nanocristales. The same growth feeds the system, because it constitutes "impurities" in a constant, and leads to a nanocrystalline composite material free from the restrictions of symmetry.

"It remains to be proven, but emerges naturally from our theory, this mechanism can explain (replacing silica by biological polymers such as proteins) how life is able to produce such complex materials with mechanical properties that are fabulous bones and shells The skeletons of the bodies, "concludes Garcia Ruiz.