Underwater time-lapse shows secret life of a coral reef
17 January 2014 Last updated at 00:29 GMT
Australia's Great Barrier Reef - the world's largest living organism - has been entrancing divers with its vivid colours and curious lifeforms for centuries.
But for one man, the glimpses he caught under water were not enough - he wanted to see more of the life hidden from most people.
Using time-lapse photography, Dr Pim Bongaerts of University of Queensland's Global Change Institute has spent the past five years documenting the movement, communication and even violent interactions that living corals engage in.
It is all behaviour that is part of the life cycle of a coral reef, but happens too slowly for us to see.
Dr Bongaerts shared some of his remarkable time-lapse footage exclusively with the BBC, and revealed some of the underwater mysteries that it has brought to life.
Time-lapse footage courtesy of Pim Bongaerts
Video journalists: Victoria Gill and Damian Fasolo
Real Time is a series for the BBC News website in which ordinary people tell their own extraordinary stories.