Cephalopods don't need a mirror test - they are mirrors themselves .

PZ probably already knows about this, but I found this discovery of super-reflective skin cells in squid, cuttlefish and octopus quite amazing!

Hanlon's team discovered that the bottom layer of octopus skin, made up of cells called leucophores, is composed of a translucent, colourless, reflecting protein. "Protein reflectors are very odd in the animal kingdom," says Hanlon, who is a zoologist. What's even more odd is just how reflective these proteins are -- they reflect all wavelengths of light that hit at any angle. "This is beautiful broadband reflection," Hanlon told the Materials Research Society at their meeting in Boston last month. The result is a material that looks startlingly white in white light, and blue in the bluish light found beneath the waves. "These cells also match the intensity of the prevalent light," says Hanlon's research associate Lydia Mathger. All this helps the creatures to blend into their surroundings.

Hat-tip: Matt Dowling