Wetzsteinchen Boulder

The field name "Auf dem Vitgensteinchen", later converted to "Wetzsteinchen", refers to this ancient stone chunk, which is now surrounded by bushes.Once a year, according to an old legend, a bird comes, sits on the stone, whets its beak on it and then flies away again.
When the stone is worn, the end of the world should be near.After that, mankind will be able to live on for a few thousand, even millions of years - the colossus cannot be broken down that quickly.In 1976, the Seibersbach community considered whether to erect the stone, probably a relic from the Ice Age, as a memorial for victims and missing people from the world wars in the cemetery.After careful consideration, this project was later abandoned due to the size of the stone and a smaller stone was placed next to the cemetery hall.Source: seibersbach.de/wetzsteinchen

A very old woman who lived next door on the farm told me that women who wanted to become pregnant would go to the stone and rub their hands on it. The stone should make fertile. For me it is a crooked menhir. If you look closely, you can see other stone settings nearby.
It can't be an Ice Age boulder, since there were no glaciers here.

After reading the insightful comments, I looked at the stone with different eyes