Although it is a natural inhabitant of the Great Barrier Reef, the crown-of-thorns has, in recent years, undergone several population explosions.

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The remaining two-fifths, they say, was predation by the crown-of-thorns starfish.

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The World Wildlife Fund offers a commercial tour in Palau, Micronesia on which snorkelers can help their guide remove the invasive crown-of-thorns starfish, which every day eat their weight in coral polyps from fragile reefs.

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John Gunn, head of AIMS, said it was difficult to stop the storms and bleaching but researchers could focus their short-term efforts on the crown-of-thorns starfish, which feasts on coral polyps and can devastate reef cover.

BBC: Half of Great Barrier Reef coral lost in last 27 years

Glen De'ath from the Australian Institute of Marine Science (AIMS) and colleagues determined that tropical cyclones - 34 in total since 1985 - were responsible for 48% of the damage, while outbreaks of the coral-feeding crown-of-thorns starfish accounted for 42%.

BBC: Half of Great Barrier Reef coral lost in last 27 years

They had spent months on it, secretly collecting firewood, carving it -- the cross and the body -- using radio wire for a crown of thorns.

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At Phillips, an untitled Basquiat charcoal and crayon work on paper shows a black man, Christ-like beneath a crown of thorns.

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