The invention provides a method of inhibiting microorganism growth comprising contacting a substance susceptible to microorganism growth with an amount of a non-decomposed moss effective to inhibit microorganism growth, wherein the moss is selected from the group consisting of sphagnum papillosum, sphagnum cristatum, and mixtures thereof. The invention provides a device for use in water comprising a carrier having an interior cavity and one or more openings allowing ingress to and egress from the interior cavity； and a moss contained within the interior cavity in which the carrier completely encloses the moss.
