On Friday, Prince William took part in an Instagram Q+A session, answering questions about his Earthshot Prize, which will see a winner announced on Sunday.
DISCOVER: Prince William unveils his stunning home office view – and we're jealous
Although many of the questions concerned the environmental project, the Duke did have to deal with some more leftfield ones, including one about the existence of unicorns. Responding to the question, William chuckled and then spoke about his daughter Charlotte, as he revealed: "Well I think if you talked to my daughter, she'd say they were real."
The royal then teased: "Obviously, it's a trade secret so I can't possibly comment."
WATCH: Prince William makes surprising comment about Princess Charlotte
Elsewhere in the Q+A, William spoke about what inspired the prize, explaining that it came from him "seeing some amazing places and seeing some amazing people doing incredible work" and he hoped that Earthshot would give them a "platform and show people that we can fix this stuff".
When asked about whether giving out a prize would help solve the issue of climate change, the royal said he believed the "hope" and the "optimism" that the prize would deliver could help.
MORE: Prince William and Kate Middleton join Steve Backshall and Helen Glover at Kew Gardens - best photos
RELATED: 10 sweet photos of royal kids wearing adorable autumn outfits
In more personal questions, the father-of-three answered one question in Spanish, confirming he could speak the language, and expressed his interest to travel to Brazil at some point in the future.
In recent interviews, Prince William has spoken about his children, and in one revealed that his eldest son, Prince George, was becoming more aware of environmental issues.
The Duke chuckled when he saw the question
"He is acutely aware, more so than the other two at the moment," he told BBC Newscast. "Charlotte is still a little bit young. She's still not quite sure. And actually, Louis just enjoys playing outside the whole time. He lives outside.
"But I think it is slowly dawning on them that these things matter. But I think when you're that young, you just want to have fun and enjoy it. I feel bad, I don't want to give them the burden of that worry."
He also expressed his concern for people from George's generation, after the young royal took part in a litter collection project at school.
Charlotte is a firm believer in unicorns
"So George at school recently has been doing litter picking and I didn't realise but talking to him the other day he was already showing that he was getting a bit confused," he explained.
MORE: Prince William and Harry’s favourite childhood meal is a royal treat - recipe
MORE: Prince William and Kate Middleton's unusual sleeping arrangements at London home revealed
"[He was] a bit sort of annoyed by the fact they went out litter picking one day and then the very next day, they did the same route, same time and pretty much all the same litter they picked up was back again.
"And I think that for him he was trying to understand how and where it all came from. He couldn't understand, he's like, 'Well, we cleaned this. Why has it not gone away?'"
Make sure you never miss a ROYAL story! Sign up to our newsletter to get all of our celebrity, royal and lifestyle news delivered directly to your inbox.