Oh sorry, It´s a raw egg shell I was meaning, perhaps I made it not so clear. When you fried an egg, do not throw the shell, wash the inside of the shells to remove the egg white film that is clinging to it as this migh develop molds and attrack insects. Then, with a mortar and pestle or a blender, you can blend the shell to make a powder. Or you can simply crash the shells and distribute these to the plant.

Btw, you live in Germany? Do you speak German?