Classroom Questions Questions for ‘Researchers get creative for underwater coral reef rehab’ When corals become stressed, they expel their algae and turn white. U.S. Geological Survey/Flickr Share this:EmailFacebookTwitterPinterestRedditGoogle ClassroomPrint By Science News Explores November 8, 2016 at 1:21 pm To accompany feature “Researchers get creative for underwater coral reef rehab”