Coralbots will be trained to distinguish coral fragments from other objects, such as sponges and other sea creatures, as well as rocks and trash. (Source: Murray Roberts/Heriot Watt University, Edinburgh)
Fascinating, Ann. I take it they would rebuild by using broken pieces of coral -- or perhaps supporting coral that is beginning to break. This could be a big deal given that coral reefs are in bad shape all over the globe.
I also wish we'd been able to see what they look like. It's worth remembering that the by now famous U of PA's flying robot quadrotor swarm learned to build things https://www.grasp.upenn.edu/success_story/grasp_lab_drones_colbert_report as did a similar swarm in France http://www.designnews.com/author.asp?section_id=1386&doc_id=249645&image_number=2 Building things is what the coral-repairing swarm will do, so it's not hard to imaging that, assuming the robots stay waterproof, they'll be able to rebuild the reefs pretty quickly, especially with enough of them.