At the Hirschkopf near Mössingen, on April 13, 1983, 700,000 truckloads of rock slid down into the valley – a “biological ground zero” was created. After more than 20 years, the slide area has developed from a hostile scree desert devoid of humus into an ecological treasure and was included in the UNESCO list of national geotopes. This DVD gives an insight into the principles of natural balance and shows symbioses as well as the fight for survival in flora and fauna. This example enables the pupils to directly experience a succession – the resettlement of a biotope – over the course of twenty years. Diverse pictures and rare close-ups offer the pupils a new approach to the indigenous flora and fauna. This DVD is divided into six chronological chapters that can be accessed individually via the menu. Moreover, it offers additional pictures and extensive accompanying material to allow a more detailed discussion of the topic at school.