Some animals — in particular certain butterflies, moths, and caterpillars — have big fake eye spots. Their purpose is to scare off predators.
Do they work? I can speak from personal experience.
I was about four years old, playing in a neighbor’s yard, when a caterpillar fell out of a tree and onto my hand. It was green and terrifying. I shook it off my hand and ran home screaming.
My mother tried to assure me that it was just a little caterpillar and wouldn’t hurt me.
“But it had mean eyes!” I insisted.
I suffered no lasting psychic harm from the event and never developed a fear of bugs. I hope the caterpillar was okay, too. Objectively, though, it did have mean, scary eyes — and they worked.