They're cute, quiet and surprisingly controversial. One of the most popular pets trending across the United States is actually illegal in some cities and states.
They're hedgehogs.
With their pointy noses and porcupine-like quills, the Lilliputian pets have seen a spike in popularity in recent years due in part to the prevalence of websites such as Cute Emergency and Instagram accounts like @biddythehedgehog that affectionately refer to them as "hedgies."
But some say the exotic animals have no place being domesticated.
"There always are ethical and moral issues with keeping exotics," Dave Salmoni of Animal Planet told ABC News. "In the case of hedgehogs, one of the big cons is that it is a nocturnal animal. So the pet owner either lets it sleep all day or takes it out of its enclosure to interact with it at a time in the day that the animal should be resting."
Champions of the pet disputed that opinion.
"Hedgehogs in the United States were all bred in captivity (they were imported from Africa in the 1970s), and they cannot exist out in the elements," wrote Deborah Weaver, president of the Hedgehog Welfare Society in an email to ABC News. "While hedgehogs are nocturnal, they respond very well to being up and about during the sleeping hours."
The majority of hedgehog owners do try and respect the nocturnal nature of their family member, she added. Based in Chaplin, Conn., The Hedgehog Welfare Society serves as an education resource for pet owners as well as a rescue and rehabilitation center for hedgehogs that are in need.
An animal may need to find a replacement home, for instance, if it is not allowed as a pet in your city or state.
New York City health code considers hedgehogs wild animals and therefore unsuitable to keep in the home. For similar reasons, states including California, Arizona, Georgia, Hawaii, and Maine have also designated them illegal. Still, a permit can sometimes be obtained for educational purposes.
"Every state is different in how their laws are set up," said Salmoni. "The laws and regulations also change often, so getting in touch with your local Fish and Game official may be a great place to start.
Another issue that can make hedgehogs tricky to domesticate is socializing them at an early age so that they are receptive to being held by humans.
"A socialized hedgehog will not mind being picked up and will lay its quills flat as a gesture of trust," longtime Massachusetts-based hedgehog breeder Jill Warnick writes on her website. "If it does not unroll after a few seconds and begin exploring, this animal has probably not been socialized at a young enough age, and will probably not make a good pet."
But those with sensitivities to dander from other animals may find that hedgehogs can offer a cuddly pet alternative with relatively low maintenance.
"These animals make wonderful family pets (albeit, not with families with very young children)," wrote Weaver in an e-mail to ABC News. "They are quiet by nature, emit no odor, typically cause no allergic reactions, and can be housed in a relatively small space (mine are in 3’ x 3’ cages) so are perfect for apartment living."
Just don't expect to go on long walks together.
"For people who want something that they can play with, a hedgehog is not for them because they don’t do much,” Amanda Munz told the New York Post, referring to her 3 1/2-year-old pet. "Gizmo cuddles and sleeps and that’s it."
Ed. note: This article has been edited since its original publication.