Mystery Photo: Prickly Puzzler on the Reef

What is this bizarre, spiky-looking organism? Hint: it can be found in tropical areas of the Pacific and Indian ocean basins crawling slowly over coral reefs and devouring any living coral polyps that it encounters. “Outbreaks” of this organism can devastate entire reef systems. Click here to reveal the answer.


David Burdick/NOAA Photo Library