sand fly

Rolling grains of sand hit each other "like billiard balls, " said Kirby, and briefly fly into the air.

Instead, it secretes a glue and USES this to stick bits of sand together to form its casing, in the way that a freshwater caddis fly larva does.

It took photographer Joel Sartore three months to get the permit required to capture, photograph, and release a single fly from its threatened sand dune habitat in California.