Aqua Culture Glowing Ceramic Moon Stone 3-Pack Create a playground for your fish with this fun Glowing Ceramic Stone Moon. It is a brightly colored ceramic stone with glow-in-the-dark edges. This colored stone is all-natural and achieves its glow using rare earth crystals encapsulated in the glaze. This creates a moonbeam blue glow that lasts for hours around the edges of each hole. This box includes three different types of stones: cozy cave with one hole getaway tunnel with two holes and the playground with three holes.