CaribSea Shelf LifeRock is the perfect way to create a stable base for your rock structures. You can stack pieces up to design caves, or even build up backwalls with its unique flat side, and the flatter surface is perfect for mounting many encrusting corals. Every LifeRock from CaribSea has an artificial coating and texture that mimics natural coralline algae. LifeRock is infused with spored bacteria to aid in biological performance, creating a mature looking reef instantly. It is 100% safe for all marine animals, unique, and environmentally friendly.