Janus the spur-thighed tortoise (Testudo graeca) turned 25 years old this year! Tortoises tend to be long-lived so that wouldn't be remarkable except that Janus is two tortoises in one: two heads, two hearts, two sets of lungs. While human mythology is fascinated by such rarities– after all, he's named for the ancient Roman god with two heads!– they tend to come with a lifespan measured in days, if not minutes. But this particular tortoise hatched at the Geneva Natural History Museum and all the humans there doubled down on giving him the best possible care. Twice as fortunately, his (their?) biology works well enough that careful oversight and some vaseline keeps him scuttling right along, healthy as can be.
And for the curious, his keepers say that both heads have different personalities. "The right head is more curious, more awake, it has a much stronger personality. The left head is more passive and loves to eat."