Near the Cason di Lanza, along the forest road that goes up towards the Val Dolce, outcrops of grey limestones from the Middle Devonian can easily be seen. You can pick out numerous fossil remains. The most abundant, which appear as thin tubes, are Stromatoporoids, distant relatives of the current sponges that lived in the lagoons protected within the bodies of the reef. Sections of some corals and the rather rarer brachiopods can also be distinguished. These rocks are called informally “Stromatoporoid limestones” due to the abundance of the remains of these organisms.