Low shipping rates with FedEx's service. Live Rock is an absolute necessity for all saltwater aquariums. They're living filters that will increase your success of keeping marine life ten fold over tanks that don't have it.PRE-CURED and HAND-PICKED LIVE ROCK Saltwaterfish.com offers the very best "Pre-cured" Caribbean Live Rock. Each piece that is shipped to our customers is hand-picked for size and coralline coverage. In the Caribbean, the rock is scrubbed down and power sprayed to remove debris. The rock is then placed on shelves where it is sprayed down with saltwater in order to allow many of the unwanted "pests" to crawl into the tanks below. Once it reaches Saltwaterfish.com it is rinsed again and placed into our Live Rock Curing System.This live rock is ancient elkhorn and other corals that have been re-encrusted over with coralline algae, sponges, tunicates, macro algaes, and other invertebrates. Caribbean live rock has many openings due to its plating structure which allows your aquarium to have better circulation, and a natural appearance. It also gives you plenty of locations to place corals.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!IMPROVES WATER QUALITY AND IT'S BEAUTIFUL There are a number of reasons why Caribbean Rock has become so popular in the aquarium trade. Most importantly, it's a natural filtration device which aids in allowing an enclosed aquarium system to flourish. It's also porous, lightweight, and comes in excellent shapes, which will give your tank a natural look for both you and your aquarium inhabitants. The porous surface and crevices of Caribbean Rock causes it to have an increased surface area, which results in great places for all micro and macro life, like beneficial bacteria and copepods, to flourish and multiply. And on top of all that it looks great too! Caribbean Rock are also usually covered with coralline algae--a hard encrusting algae that comes in colors of green, purple, blue, and pink. Plus, Caribbean Rock will often times have coral skeletons and other mineral deposits that are conducive to keeping marine life.Note: The weight listed is the total weight including packaging.