Salvinia natans is a floating aquatic plant which can appear superficially similar to moss. Salvinia natans has two nickel sized leaves lying flat against the surface of the water, and a third submerged leaf which functions as a root. Floating is made possible by pouches of air within the leaves. The leaves of Salvinia natans block sunlight from reaching very far underwater. This is helpful to many freshwater fish, providing safe hiding places to breed.