OOTDTYChs: Put the stone in good sunlight or a bulb for about 20 minutes and it will absorb the light and glow in the dark for about 2-3 hours. Make your aquarium or vase even more unique. These rocks are made in different shapes of pine cone in different colors and will be sent for decoration and wow your aquarium. All pebbles are made of acrylic, eco-friendly for fish and plants. Use these pebbles to decorate aquariums, fish tanks, vases, water features, landscaping, garden walkways, yard grass, flower pots and some decorations for your DIY home. Wrapped in a clear jar, these glow stones make a great gift for family and friends. Specification:Material: AcrylicWeight: Approx.200gPackage Included:1 Pack of Aquarium RockNote:1. Please allow 1-2cm errors due to manual measurement, please make sure you do not mind before ordering.2. Due to the difference between different monitors, the picture may not reflect the actual color of the item.