Researchers closely studied the wings of two moth species from China and Africa, and found that their tiny scales form a "metamaterial" that absorbs bat sonar — thus becoming an acoustic cloaking device.
Pretty darn cool. The paper is paywalled here, but Nature has a good lay-persons' writeup …
— Read the restThe researchers measured the acoustic reflections from wing sections of two moth species (native to Africa and China) in the ultrasonic range of 20–160 kHz typically used by bats for locating prey.
