Banaba was at one time a primary source for rock phosphate. Here's a bit of a definition: rock phosphate is formed from bird droppings or animal droppings that have dried up and built up over a long period of time—talking millenniums here. And, of course, with the people there as well, the connections that they have with the environment informs their cultural practice. This, combined with sulphuric acid to make super-phosphate, was the main fertiliser used in New Zealand's pastoral farms since the 1930s. From the early 1920s until the mid-1980s, phosphate was New Zealand's main export from the Pacific.