  I'm watching some documentary about vision, and they just said that if you're in front of a cobra and stay still, you will become invisible to it, since the sensor cells in their eyes get tired after a while of no movement, and therefore you become no longer noticed by their eyes for as long as you stay still.
This is good to know since most cobras would rather run away than attack you, and will only attack if they feel they are in danger. So, if you ever see one, you better keep still, motherfucker. Another odd fact they said is that lobsters can only see in 12 colours. (Didn't the Atari or some silly game console have a similar number of colours back in the day? ) 
