Kloud City 3.65oz Colorful Luminous Resin Stone, Cobblestones, Pebbles Glow in the Dark for Aquarium, Fish Tank, Plant Flower Pot Decoration 1 bag weigh 3.65oz, it has 30-34pcs stones Designed for use in Aquarium ,Fish Tanks, Pools, & Ponds. Can also be used for Gardens and Home Plant pots After sunlight, the stone would be more brighter in dark. Not natural,main material are fluorescent powder and resin.