Penn Plax The Reptology Granite Stone Hide-Away - Large PERFECT FOR COMFORTABLE HIDING AND RESTING: the granite stone replica is hollow with a round entryway, mimicking what is found in a natural habitat. Helps reduce stress and aggression, especially in fish. DURABLE DESIGN: made of safe durable resin, this ornament is safe to use in all terrariums and aquariums. FOR A CUSTOM LOOK: display this ornament alone or combine it with additional stones or plants for a custom environment (each sold separately).