The world's biggest coral — an organism made up of about a billion polyps — is about three times bigger than the previous record-holder and was discovered by chance during an expedition off the Solomon Islands.

The largest coral ever recorded has been found by scientists in the southwest Pacific Ocean. The mega coral - which is a collection of many connected, tiny creatures that together form one organism rather than a reef - could be more than 300 years old. It is bigger than a blue whale, the team say.