http://www.bbc.com/earth/story/20161121-the-great-barrier-reef-is-twice-as-old-as-the-human-species
Once a year, all the corals on Australia's legendary reef get together to reproduce.
At 7:30pm local time on 21 November 2016, the corals of the Great Barrier Reef took part in "their annual sex festival" – as Chris Jones of the Great Barrier Reef Marine Park Authority calls it.
"It's a mass coral spawning event," says Jones. "Sperm and eggs are all released into the water at the same time and they join up."
