A Brazilian biologist and a team of volunteer divers are killing coral to save a marine protected area just off the famous Ipanema beach.

They’re manually removing sun coral, an invasive species first seen in Brazil more than 40 years ago, from an offshore oil platform.

The coral has no natural predators in the region and it has spread along the coast, where it could suffocate Brazil’s marine wildlife.

So Adriana Gomes and her team are using a simple but effective technique to solve this problem: Their own hands. Watch the full video to see if they succeed.