Corals have populated the world’s oceans for as long as 500 million years. At first glance, the fossil representatives are barely distinguishable from their modern relatives. However, a detailed inspection reveals that the prehistoric corals showed a different structure than any of their living representatives. The Tabulata, which also include Pleurodictyum, are primarily colony-forming corals, i.e., several polyps construct a joint coral outcrop. At the end of the Permian, approx. 250 million years ago, they disappeared without a trace, and only several million years later, coral reefs were once again documented in the fossil record.