Roman coliseum cave 9"x7.8"x4.3" Aquarium Ornament Decor aquatic Arena Colosseum Ornament is made from non-toxic plastic material and makes a perfect ornament in any aquarium. Offers the natural environment feeling,change your aquarium into a beautiful scenery. It is vividly and colorful detailed to add lively and natural life to your tank. It is great to decorate your aquarium all the time with minimum responsibility and maintenance. They're are absolutely safe for fish and best of all, they won't die, rot or cause any algae problems.