The precise number of animal species that exists on Earth, both past and present, is unknown. Following this logic, there's a plethora of animals they didn't teach you about in school. Sure, lions, tigers, and bears (oh my!) are cool, but if you're looking to expand your knowledge of the Animal Kingdom or just want to stock up on fun #animalfacts, check out these nine exceptional creatures.

Before you mistakenly categorize this primate as a chimp, take a closer look. The bonobo is one of the most rare and intelligent primates in the world; they’re only found in a small part of the Democratic Republic of Congo and, among other things, their social structure is unique, complex, and largely peaceful. The agouti (ah GOO tee) is a rain forest-dwelling rodent from Central and South America. Given its diet of fallen fruit and nuts, it’s no secret that the agouti loves forest leftovers, but its sharp incisors also play a vital role in the survival of Brazil nut trees (one of the largest in the Amazon). This rodent species is the only mammal that can crack open the indestructible outer shell of a Brazil nut, which is extremely valuable for the country’s remote people. Madagascar is home to some incredible species, and the fossa is the "king" of them. Even though resembling a morphed cat-like dog, a fossa’s closest relative is the mongoose, but the misunderstandings don’t end there. Legends of fossas stealing babies from cribs, licking humans into a deep trance, and making their own pupils disappear are endless, but let’s be honest, we prefer facts over a lengthy list of myths. Imagine a buttery box of theater-style popcorn, and you can almost smell this next exceptional species. Yes, the smell that usually signifies box-office entertainment is the same smell you’ll find emanating from a binturong, aka bear cat. However, that moniker is a bit misleading since binturongs aren’t related to bears or cats but instead have closer ties to fossas mentioned above. There are only two types of egg-laying mammals in the world, and the echidna is one of them. If that’s not enough to spark your interest, this spiny anteater is also one of Earth’s oldest surviving species. While other animals have been busy evolving and adapting to fluctuating environments, the echidna has remained unchanged since prehistoric times. Speaking of anteaters, the tamandua (aka lesser anteater) is another mammal you probably didn’t know existed. Its relative, the giant anteater, gets most of the attention, but the tamandua has its own way of making its presence known; it can spray a rotten-smelling secretion that’s said to be significantly more powerful than a skunk. Thus, its unforgettable nickname, “stinker of the forest,” is properly attributed. The tree pangolin is a scaly anteater that looks like a pinecone with legs and a long tail. Its scales are made of keratin, like our hair and fingernails, which protect this “pinecone” from predators. Sure, the tuatara appears to be an average lizard, but this reptile is truly unique. The tuatara is specific to New Zealand and its closest relatives are an extinct group of reptiles that lived during the time of the dinosaurs. It’s no wonder the tuatara is referred to as a “living fossil.” Caecilians (pronounced seh-SILL-yens) live a mysterious life in a network of underground tunnels. There are over 120 species of caecilians on at least 4 continents, but almost nothing is known of this amphibian's habits or lifestyle. Can you think of any uncommon animals to add to this list? Share yours in the comments below. *Jenn Beening is the social media specialist for San Diego Zoo Global. Read her previous post, Ken and Dixie’s Bite Club.