Prince William discusses his facial scar during a recent royal engagement

Prince William has made rare comments about his facial scar.

The Prince of Wales was in Cardiff on June 11, where he met with various businesses and organisations who are using seaweed in their packaging — including catching up with previous Earthshot Prize winner Pierre Paslier, of Notpla. The company has developed a golf tee made from seaweed, which William checked out during the royal engagement.

"He was looking at the prototype, and I asked him if he likes golfing," Pierre told People about the meeting. "He injured himself famously as a kid and pointed to his head and said, 'No golf for me.' No golfing for him!"

William rarely publicly addresses the scar he got from golf, but it isn't the first time he's brought it up.

Circa 2009, the Prince joked that he calls the mark his "Harry Potter scar," according to BBC News. "I call it that because it glows sometimes and some people notice it — other times they don't notice it at all," he explained.

"I got hit by a golf club when I was playing golf with a friend of mine. We were on a putting green and the next thing you know there was a seven iron and it came out of nowhere and hit me in the head."

That sounds really painful, and we can definitely understand why William has been put off golf ever since.

Seaweed in packaging and other consumer products is one of the coolest innovations within the eco space right now — something that's obviously close to the Prince's heart.

"We’ve had the privilege of meeting him several times since we won the prize," Pierre added, speaking to People. "He really knows his stuff. He really knows seaweed."

As part of his commitment to the planet, William set up the annual Earthshot Prize, which awards £1 million each to five solutions working to reverse climate change each year. This year, the award ceremony will take place in Cape Town, South Africa, after having previously been held in Singapore, Boston, and London.