) Remove nitrates from water. 2) Increase oxygen in water. 3) Acts as a natural cave option. 4) Can be used to tie down plants. No shelf life, use forever. Does not decay or decompose. Excellent use in Mulching and for Planter Decorations. Acts as Weed and Insect Barrier. Conserves moisture and reduces watering. Long lasting colour guarantee- A permanent landscaping solution Ideal for Planting in the Aquarium. Handpicked specifically. These are natural rocks and hence no two rocks will look similar.