The Steinerne Rose is a rare natural monument. It is a diabase rock formation, that originated on the sea bed from outflowing lava in the middle Devonian, i.e. about 400 million years ago. The lava formed pillow-like bodies which have an internal structure of concentric layers. Over thousands, if not millions, of years these layers have been weathered out (exfoliation joints), giving the bodies the appearance of rosebuds in bloom.