The Underwater Gal New Moon Rock is a wonderful pale blue in the daylight with a magical aqua blue glow at night! This amazing cave is 100% natural and completely safe for all aquariums! The glow comes from rare earth elements added to our special glaze which absorb light from a nearby source and give it off again when the lights go out! 
special ceramic glaze fired on at over 1500 degrees F, so it will last for years
 to activate glow, just provide a strong, light source above it. (Florescent and incandescent bulbs are best as aquarium tank hood lighting.) Natural sunlight from a window is good for small fish bowls; or a desk lamp.