Millions of years ago, a warm sea splashed where modern streets now lie, the traces of which are still hidden in stone. In the lecture, one can examine the fossils of ancient beings, learn what the reefs of past eras looked like, and understand why the stories of prehistoric oceans are important for us today, curious schoolchildren and adults alike. Imagining that familiar neighborhoods were once the bottom of a warm sea is not easy until you hold living evidence in your hands. The meeting will discuss the ancient basin that existed in the Ural region hundreds of millions of years ago, the changes in climate and relief, and the creatures that inhabited the clear waters. Together with the lecturer, participants will trace how a chaotic collection of stones forms a complete picture of the past. The main focus is on the findings that are usually hidden behind strict showcases. Sea lilies, urchins, trilobites, brachiopods, and mollusk shells will appear not as dry illustrations from a textbook, but as heroes of a grand story. It becomes clearer how the reefs looked, what they were made of, why some species have only survived in fossilized form, while others became ancestors of modern life forms. A separate discussion is dedicated to the predators of the ancient sea and the traces they left in the rocks. Where to go in Yekaterinburg is known by KudaGo.