This rock reminds us of the old Tonga rock that was available years ago. Although it is no longer available we feel this is a better rock for your system. The Branching of this rock is quite unique and provides an array of endless possibilities. This rock is cured and ready to become a centerpiece of your aquarium display.Once you receive your rock, you must re-cure the rock for at least a week. During shipping some of the beneficial bacteria will die off. Do not add this directly to an existing tank!