Expecto Patronum! Harry Potter fans got a special treat when a new quiz allowing them to discover their Patronus launched on the Pottermore website on Thursday, September 22.

For those muggles out there, a Patronus, which takes the form of an animal, is a kind of positive force that protects wizards from Dementors (evil black spectral beings that feed upon happiness, hopes and dreams).

The animated quiz on the official Harry Potter website asks fans to relax and think of their happiest memory as they complete a number of questions. At the end their Patronus is revealed. Fans have been sharing the result on social media, with animals including cats, dogs, birds and even mythical unicorns. (For the record, Potter’s Patronus was a stag, while J.K. Rowling’s is a heron.)

Harry Potter author Rowling incurred the wrath of some fans on Thursday when she jokingly retweeted a doctored image of Harambe the gorilla as a Patronus.

As Us Weekly previously reported, the 400-pound male gorilla was shot and killed at the Cincinnati Zoo back in May after a 4-year-old boy fell into his enclosure, leading to a life-threatening situation for the child.

The death of the 17-year-old western lowland gorilla, an endangered species, sparked outrage among animal lovers around the world.

“I’ve been asked to make it clear that Harambe is not a Patronus you can actually get on @pottermore,” the author tweeted about an hour later. “The previous RT is a joke. As you were.”

She followed it up with, “I thought it was very funny, btw.”

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