Waveroar 100 Pcs Glow in the Dark Stones Fluorescent Luminous Pebbles Rock Photoluminescent Stones for Garden Fish Tank Aquarium Walkway - Sky Blue 100 piece set of man-made pebbles Material: Photoluminescent pigment + resin Line a walkway, edge a flower bed or fill a planter with these unique acrylic pebbles Glow lasts approximately two to three hours after full sun exposure Pebbles are about the size of cooked lima beans