Coral reefs are amazing. They look a bit like multicoloured rocks but they're alive - they're made up of millions of tiny creatures and they provide a home for about a quarter of all life in our oceans. The problem is, they're dying.
The biggest ever scientific study of the state of coral around the globe was published this month. We've known for years that corals are suffering from global warming. But the new report gave us new details. Just in the last 10 years, we've lost about 14% of the world's coral, it said.
But there are signs of hope. The report found that coral in some regions is recovering. And people all across the planet are waking up to the danger and are finding solutions to the problem.
Best friends with a dream
Two of these people are in the news this week because they won a big prize - worth more than a million euros! - to help them grow new coral using a system that is super-fast. Gator and Sam met at university in America a few years ago. They now run Coral Vita, a project to save the world's coral that is based on an island in the Bahamas close to the sunny U.S. state of Florida.
Sam Teicher and Gator Halpern say they're "best friends ... almost brothers". What brought them together was their wish to make a difference. Gator says: "We started thinking and dreaming about making an impact on the issues we cared so deeply about, at the centre of which was coral reef degradation."
Says Sam: "Coral reefs are one of the most magical ecosystems on Earth."
Find out more about coral, why it matters and why it's in danger here.
Earthshot Prize offers new hope
With Gator, he is using a new technique to grow coral in tanks up to 50 times faster than normal. They can choose types of coral and change the water in the tanks to grow coral that will be able to thrive when it's planted back in the sea to revive the reefs.
This week, they were awarded one of the first five Earthshot Prizes, set up by Britain's Prince William to find the best solutions to get our planet back to health over the next 10 years.
The money, said Sam, will help them set up coral farms around the world. And you can help!
On their website and others, you can "buy" some fresh coral that will go to helping rebuild the reefs. How about getting your class to sponsor some coral?
Watch Seth and Gator accept their prize, and see some of the amazing coral reefs they help, in this video: