## 3 Results and Discussion
Barium Silico-Carbonate Biomorphs Are Possibly the First Inorganic Structure That Formed Parts of Various Forms of Life in the Precambrian  
In the case of the barium control biomorphs synthesized under the current conditions, a leaf morphology was observed (Figure 4a). The biomorphs obtained under the conditions that emulated the Precambrian showed a spherical shape (Figure 4b). To evaluate the shape, chemical composition, and crystalline structure of the barium silica-carbonate biomorphs obtained on the obsidian, the biomorphs were synthesized under the current atmospheric conditions and under the conditions that emulated the Precambrian era (50 \({}^{\circ}\)C in the presence of 5% CO\({}_{2}\)). The barium carbonate biomorphs synthesized under the current atmospheric conditions presented crystalline aggregates that resembled leaves, spirals, flowers, and stems (Figure 4c). Meanwhile, the barium silica-carbonate biomorphs produced under an atmosphere that emulated the Precambrian conditions presented a polycrystalline sphere-type morphology (Figure 4d). Shapes have been previously observed in other works under both atmospheric conditions that emulated the Precambrian era [19; 25]. In addition, these data show that, regardless of the material or mineral on which the biomorphs are synthesized, atmospheric conditions seem to be directly involved in the morphology they adopt (Figure 4). Thus, the results obtained in this work show that, under the conditions that emulated the Precambrian, the biomorphs obtained tend to be sphere-like structures (Figure 4). This spherical shape has also been shown in biomorphs synthesized in the presence of biomolecules [19; 22; 34; 70] and of different clays [31], as well as in atmospheric conditions that emulated the Precambrian [70], which is possibly due to the fact that it is the most thermodynamically stable morphology, considered to be characteristic of life [70]. The fact that previously observed crystalline aggregates under these same atmospheric conditions have been identified indicates that obsidian is a good support for the synthesis  
Figure 4: SEM micrographs of the barium silica–carbonate biomorphs synthesized on glass (**a**,**b**), on obsidian (**c**,**d**), under (**a**,**c**) ambient temperature, and (**b**,**d**) conditions emulating the Precambrian atmosphere. of biomorphs. This fact is important because it has been described that biomorphs, when obtained on other support surfaces under the current atmospheric conditions, present the shapes of leaves, flowers, and helixes (twisted structures) [27], similar to the barium carbonate biomorphs synthesized on obsidian (Figure 4c). In the case of the biomorphs produced under the conditions that emulated the Precambrian era, which present a sphere morphology (Figure 4d), it is noted that this is the morphology that also appears when biomorphs are synthesized at low temperatures of 4 \({}^{\circ}\)C and \(-20\)\({}^{\circ}\)C [33], as well as in the presence of biomolecules such as proteins and nucleic acids [22; 23; 34]. The evidence indicates that crystalline aggregates of barium, which took part in supporting the first forms of life, were possibly spherical, which, by being the most stable shape, allowed for improved survival, together with other environmental factors and the primitive metabolism of these lifeforms (which, in some cases, have continued to exist up to the present day). It has been reported that Ba\({}^{2+}\) has been identified in algae, in some invertebrate species, and in fish in the Irish Sea [71]. Once the morphology of the barium silica-carbonate biomorphs obtained under both atmospheric conditions was observed, the identification of their chemical composition and crystalline structure was carried out via Raman and FTIR spectroscopies and PXRD analysis.