A “Hühnergott” (adder stone) is a type of stone with a naturally occurring hole through it. Commonly, they are found in Northern Germany at the coasts of the North and Baltic Seas. The café with this name was closed, maybe we were lucky, because the seats don’t look very comfortable.
Geriatri'x' Fotogallery 
Those seats would be better with cushions to sit on!🙂😊
Perhaps there are some, when it is open.
They don’t look comfortable, but it might be fun to swing a bit as you sip.
Lovely seats.