The dark brown sponge nestling about four metres underwater in a glorious coral garden in the Bunaken marine national park off the northern tip of Indonesia’s Sulawesi island looked remarkably ordinary.

But Ove Hoegh-Guldberg, a marine biologist at the University of Queensland, became extremely excited when he saw it. “That sponge [species] is about a billion years old,” he said, dipping his head down to take another look. “It was around before there was oxygen on earth. That’s the sort of thing this project is all about.”