Coral is very slow to recover from any damage. If someone touches coral, that section of coral could die. Coral is made up of thousands, if not millions of small oraganisms (polyps). If a "chunk" of coral is broken off, it grows back very slowly, the fastest growing (staghorn) only grows 1 inch every year. If you see dead or damaged coral, it probably won't make a full recovery in our lifetimes.