During the mid-19th century, Peruvian bird poop was big business. But in just a few short decades, the excrement boom went bust. The cycle began with Prussian geographer Alexander von Humboldt, who visited Peru in 1802 and noticed workers unloading shipments of dried droppings, imported from the Chincha Islands. Produced by a native bird called the Guanay cormorant, the poop—which was referred to as guano—made a great fertilizer. It was also used to make gunpowder, and when mummified human remains were found preserved in piles of guano, curiosity seekers from around the world attended touring exhibitions to see the desiccated bodies on display.

Learn why the world went crazy for guano, why demand for it diminished over time, and how the stinky stuff replenishes nutrient-depleted soil by watching the video below, featuring the SciShow’s Hank Green.

[h/t SciShow]