The Utrish Nature Reserve is a mountain forest and sea UNESCO World Heritage Site. The beaches are pebbly and bouldery. In winter, after strong storms, they change to sand and shell. Travelers do not know about this in the summer. The sea reveals its secrets only in winter. On the beaches of the Black Sea coast, there are many interesting minerals of various shapes. The storm throws pieces of rock into the sea, which are processed and smoothed by the surf. This specimen is "zebra stone", a type of argillite, has a layered structure, the color is dark blue and light gray. Argillite is a mass of clay that has hardened as a result of millions of years of mineralization.