They are the weirdest looking animals with a bill like a duck, a tail like a beaver and feet like an otter. Apparently they thought it was a hoax when first encountered and I can see why.
The platypus (Ornithorhynchus anatinus) also known as the duck-billed platypus is a semiaquatic egg-laying mammal endemic to eastern Australia, including Tasmania. Together with the four species of echidna, it is one of the five extant species of monotremes, the only mammals that lay eggs instead of giving birth. It is the sole living representative of its family (Ornithorhynchidae) and genus (Ornithorhynchus), though a number of related species have been found in the fossil record. You can read all about it here: https://en.wikipedia.org/wiki/Platypus