Science has identified some 2 million species of plants, animals and microbes on Earth, but scientists estimated there are millions more left to discover, and new species are constantly discovered and described. The most commonly discovered new species are typically insects, a type of animal with a high degree of biodiversity. Newly discovered mammal species are rare, but they do occur, typically in remote places that haven't been well studied previously. Some animals are found to be new species only when scientists peer at their genetic code, because they look outwardly similar to another species — these are called cryptic species. Some newfound species come from museum collections that haven't been previously combed through and, of course, from fossils. Read below for stories about newly discovered species, both alive on Earth today and those that once roamed the planet.