Will a spaceship land in Pilsen? Mysterious shapes on the roads surprised not only motorists

Two white squares touching one corner. Mysterious signs have appeared on roads in and around Pilsen in recent days. They are painted in lanes or on curbs, and their occurrence has no regularity. The images are discussed by people on social networks. As the editorial staff of MF DNES found out, these are not signs intended for drivers or the work of sprayers.