"Window of opportunity closing" to save world's coral

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Reefs declined by 14% worldwide over the last decade but scientists say they could come back. Facebook boss Mark Zuckerberg has apologised for a technical failure that left users worldwide unable to access his his company's social media platforms. And a team of French and British physicists has devised an ‘invisibility cloak’ - so why are they doing it and what can it be used for?