Answer: Platypus

Mites are microscopic arthropods that are among the most diverse and successful of all the invertebrate groups. They’re so successful that for the vast majority of us, creatures big and small, mites are just a fact of life. While you’re reading this, there are mites in your eyelashes, mites on your skin, mites on nearby textiles like rugs and pillows, mites on your pets, mites on the birds perched outside your window, and mites on the insects buzzing about your yard (there’s even a specific mite that attacks only honey bees).

In fact, if something crawls, walks, slithers, flies, swims, or just lazes about in place for all of its life, there’s at least a mite or two that uses it as a host. There is, however, a curious exception to this rule in the mammal kingdom. Of all the mammals ever checked for mites, the only ones that apparently have no mite species colonizing their bodies are the already-curious-enough creatures in the Ornithorhynchidae and Tachyglossidae families (that are populated, respectively, by the platypus and its echidna relatives like spiny anteaters).

For reasons that are unclear, mites simply have no interest in the oddly shaped semiaquatic egg-laying mammal and its monotreme cousins found in Australia and New Guinea. Perhaps they, like the early European scientists that came across them, were off-put by the strange and inexplicable mishmash of body parts and/or biological functions found in these odd mammals.