They’re hypnotic and incredibly odd. Thousands of black plastic “shade balls” were released this week into the Los Angeles Reservoir to float and bob on the surface, looking like a kind of dark playground ball pit.

The release of this batch of 20,000 balls into the 175-acre reservoir was the culmination of a $34.5 million initiative to protect the water supply that involved the deployment of a whopping 96 million plastic balls into the water. Read more.