Among the animal specimens collected by John Hunter (1728-1793) was this tiny fetus of a three-toed sloth (bradypus tridactylus). Hunter would have been interested in this specimen for his studies in comparative anatomy, but to my modern eyes this creature looks completely alien — in fact, it's the closest thing to the cinematic E.T. that I've ever seen. Today, this sloth is part of the Hunterian Museum at the Royal College of Surgeons of England.