The structure of Vulcano would seem unable to accommodate anything edible. On the other hand, we are talking about an island that was never inhabited until the 1960s.
In fact, in recent years, many plots of land in the southern part of Vulcano, the part not currently active, have been used for sheep farming. It is quite common to find goats and sheep grazing freely all over the island. The volcanic cheese has become famous, especially the baked ricotta, produced and packaged exclusively on the island.
