Although they are considered small-scale ecosystems, microbial communities have had a major influence on the development of life on Earth. To get a clear picture of life on our planet billions of years ago, researchers need to investigate fossils. To see to what extent different environmental conditions influenced the formation of fossils, it is very important to look at modern analogues of archaic sedimentary structures. One such analogue is the modern stromatolite formed around the geothermal spring at Ciocaia in the Western Romanian Plain. Although the microbial community at Ciocaia was formed under conditions similar to other thermal springs in the Western Plain, sedimentary formations have been observed only at Ciocaia. The aim of this project is to investigate the diversity of archaeon and bacterial diversity in the Ciocaia microbiallite in comparison with other thermophilic, non-mineralised microbial communities. This investigation is very important to explain the mineralisation process as it can indicate whether there is a correlation between microbial diversity and the formation of sedimentary structures. The study of archaeon and bacterial diversity will be carried out using three molecular biology techniques in order to obtain optimal results.