This watch glass-shaped hill was formed as a precipitate from the carbonated brine spring "Unitas". The spring itself built up this rock, which is over three meters high, on the open plain above the Heder gravel. The age of the lowest layers of the sintered rock is estimated to be more than 15,000 years.
Close to the Kütfelsen is the well house, which was built in 1554 and is now a listed building. It was lovingly restored in 1980/81 with funds from the Westfalen Office for the Preservation of Monuments. The well house was built directly above the brine spring in order to provide sufficient protection for the "Unitas spring"