The Exo Terra Moss Ball is a natural water conditioner and decorative item for aquatic terrariums. Made from synthetic resin with absorbent moss fibers, it helps reduce odor and improve water quality by absorbing waste and phosphate. When placed in a turtle’s water dish or aquatic tank, the “moss ball” inhibits the growth of algae and keeps the water clearer for longer. It also provides a visually pleasing, natural accent in the water feature of your terrarium.