The ‘greened’ slate stones with Aegagropila pads offer attractive design options in the foreground to midground of any aquarium. Aegagropila, also known as Moss Ball, is a green algae that grows in a compact form in Eastern Europe and East Asia. The water-neutral slate stones are a natural German product from the northern Eifel region, where they are traditionally used to clad roofs, gables and façades.