On Monte dos Bicos (Punta Herminia) there are two petroglyphs: the Pedra do Altar or the Altar Stone, which is in a poor state of conservation due to bullet impacts during the time this was a military zone, and the Peña de la Brújula or Pedra do Compás (Compass Stone). They feature a series of cruciform figures which, at the beginning of the 20th century, were considered to be prehistoric art. However, since the mid-20th century, they have been classified as jurisdiction boundary markers, perhaps dating back to the Middle Ages.