CaribSea LifeRock Flatz 20 lbReal aragonitic base rock, not cement, no curing. Extensive macro and micro-porosity infused with spored bacteria for outstanding biological performance. Clean and safe for all fish and inverts, environmentally responsible each piece is very unique.Shipping Notes:This rock is fragile and can incur damage during shipping. We are not able to insure rocks therefore we can not replace nor refund broken pieces. Most broken pieces can be repaired with epoxy or coral glue.