With our huge range to select from, these beautiful copies of real rock are a must for every aquarium or terrarium. No need to worry about weight. You can create that look and feel you would typically see in a public museum or Zoo yourself. Available in foam or our flexible material. Make sure you order the right product! The foam rocks will float in Aquarium unless siliconed in place. To create a pretty cool look and also help or get rid of any dead water you can drill some holes in these rocks and put an air hose into the rock. This will look better than a little air stone however you will achieve the same affect. These rocks when siliconed onto the side or back of the tank can then be used as a waterfall just by adding a small pump and tubing. A great look and habitat for those rainforest animals.