Book 32, Question 130
Can you tell if a snake is venomous by the shape of its head?
Some people say snakes with triangle-shaped heads are venomous, but this rule is not reliable.
Some harmless snakes flatten their heads to look scary, and some venomous snakes have narrow heads. Because there are so many kinds, even experts need a close look. The only rule you need is to leave all wild snakes alone and back away.