The peak of Teide on Tenerife can be seen on clear days from the African coast. The Carthaginian captain Hanno the Navigator may have visited the islands during his voyage of exploration along the African coast. The Phoenicians may have arrived seeking the precious red orchil dye extracted from lichen – if the Canaries represent Pliny the Elder's "Purple Isles" or the Hesperides of legend. Although no evidence has survived of any permanent Roman settlements, in 1964 Roman amphorae were discovered in waters off Lanzarote. Discoveries made in the 1990s have demonstrated in more definite detail that the Romans traded with the indigenous inhabitants. Excavations of a settlement at El Bebedero on Lanzarote, made by a team under Pablo Atoche Peña of the University of Las Palmas de Gran Canaria and Juan Ángel Paz Peralta of the University of Zaragoza, yielded about a hundred Roman potsherds, nine pieces of metal and one piece of glass at the site, in strata dated between the 1st and 4th centuries. Analysis of the clay indicated origins in Campania, Hispania Baetica and the province of Africa (modern Tunisia).