What is "kugelbake"

The Kugelbake is a historic aid to navigation in the city of Cuxhaven, Germany, at the northernmost point of Lower Saxony, where the River Elbe flows into the North Sea. In the Low German dialect of the Middle Ages, the term bake referred to all navigational aids – including lighthouses. About 30 meters (100 feet) high and built of wood, the Kugelbake is the principal landmark of Cuxhaven; since 1913, it has been depicted on the city's coat of arms. Large wooden structures guiding mariners have stood on this spot for over 300 years.