Thegreenedslate 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 faades. In aquariums, slate stones are considered an interesting alternative to other decorative stones due to their particularly flat shape. A particularly harmonious design can be achieved with a group of 3 or 5 Aegagropila Slate Rocks. Tip: If the stones become heavily mulched, they can be easily removed from the substrate and the green cushions cleaned well under a jet of water.