A tiny fish found in Indonesia's Sumatra Island is the smallest vertebrate animal in the world. The creature is called "Paedocypris progenetica" and is related to the tent, although it measures only 7.9 millimetres in length. The 'Paedocypris progenetica' adults have a transparent body, a circumstance that gives them the appearance of a larva, and they live in dark waters that have an acidity level of at least a hundred times more than rainwater.