Set in a pleasing,tranquil forest, the Growing Rock of Usterling is a magnificent example of stone troughs. Over a span of 5000 years, or this geological oddity has grown out of springs containing limestone. With a length of roughly 130 feet and a height of nearly 16.5 feet,it's the largest stone trough in Germany. Amazingly, it is still continuing to grow.
Source: atlasobscura.com