These are so-called "Geological Organs" although may not actually play "music". They are located in "Bossarts" near Memmingen, Baden-Württemberg, Germany.
The little village Bossart became public for his geological organs. These are round smooth-walled, tube-like structures which are partially filled with weathered clay. Formed by the weathering of limestone and dolomite rocks of the consisting conglomerate rock. You can see different kalkalpine rocks such as dolomite, limestone and red chert. Layers of coarse components alternate with sandy layers. In strong winds, the air vibrates in these tubes and we hear organ-like tones.
The geological organs formated around 600,000 years ago. Carbonate of rainwater has dissolved the limestone in some places, thus forming the funnel-shaped, sometimes up to 15 meters high tubes. The name for this natural monument organ derives from tubes lined up like organ pipes. The geological organs in Bossart are registered as geotopes by the Bavarian State Office for Environment. They are classified as significant and valuable geoscience as rare in number and existence.