Hobby Grotto Ceramic Puzzle is a uniquely formed aquarium decoration. Provides shelter and hiding places for fish. Ideal rooting base for attached plants and animals. Inexpensive alternative to or ideal combination with corals in seawater aquariums.Hobby Grotto Ceramic Puzzle+ individual stones can be combined individually+ numerous design options, according to individual taste+ to create decorative and mysterious hiding places in fresh and seawater+ inexpensive and ecological alternative to corals in seawater aquariums