Luminous conch shell,starfish could glow in the dark more than 6-10 hours,through absorbing the sunlight/lamplight in daytime ,can glow in the night better. Unique decoration for the fish tank and aquarium Harmless to All Fish,Fits Salt water and Fresh water Feature:High brightness , long life time Water, acid and alkali resistant, antioxidant Use environmental friendly material: no radiation, non-toxic One side of each stone is flat, for easy decoration. Designed for use in fish tank, garden ,yard ,line a walkway, wall,vase, flower pot, swimming pool,any place you want to use.Note:Not toys, keep away from children for chocking hazard!