What is the rarest pet ever?

Could you elaborate on the topic of the rarest pet in existence? When we talk about rarity in pets, we're often referring to unique species, breeds, or even individual animals that are exceptionally uncommon. Could you provide an example of a particularly rare pet, perhaps one that is endangered in the wild or a breed that is rarely bred due to its specific genetic traits? Additionally, what factors contribute to the rarity of a pet, such as its breeding frequency, natural habitat, or popularity among pet owners? Furthermore, are there any ethical considerations one should take into account when discussing or acquiring rare pets? I'm curious to learn more about this fascinating subject.