The 5 Pack Stackable Aquarium Decoration Rock Caves are perfect for any fish tank. With smooth edges and no rough edges, these caves are designed to allow your fish to swim freely without worry about being hurt. Made of high quality ceramic material, these caves are also easy to clean and provide a healthy environment for your fish. With a flat bottom and light weight design, our ceramic cave can be stacked on the ground in your fish tank to create an unique scene as well as provide more fun for your lovely fish.