Scuba diving on a coral reef in the Red Sea, I hovered over a clownfish (think Nemo) guarding its anemone. It kept darting towards my mask, clearly saying: "Keep away from my house", " I told you, keep away from my house", "If you don't keep away from my house, I will bite you".
There was no way the little fish could hurt me – it was too small – but it did make me wonder how the fish knew to communicate with my eyes rather than any other part of my body.
Butterfly fish have a stripe through their eye and a dot on their tail. This is to confuse predators in the hope they will bite the wrong end of their prey and so do less damage.
You might have noticed that you can sometimes 'see' a face in the grain of a wooden door, the shape of a cloud, or the bark of a tree.
Even babies respond to a circle drawn with two dots as if its a face with eyes.
We are programmed to recognise faces
When selling clocks, the hands are traditionally set at a particular time. Clocks have faces too, and ten to two makes it look as though they are smiling. The theory is that people are more likely to buy them that way.
If you go to Google Images and search 'Ikea clock' you will see something very interesting. I won't spoil it by telling you what that is, but it will make you smile.
Top tip: If you want to sell more, smile :-)