rounded heads.
Unfortunately, that rule is unreliable.
Some nonvenomous snakes flatten their heads when they feel threatened, making them appear triangular.
Other venomous species do not fit the simplified description.
Eye shape, color, and body markings can also be misleading when considered individually.
According to the University of Illinois Extension, head shape alone is not a dependable method of distinguishing venomous snakes from harmless ones.
Illinois
This is especially important when the animal is partially hidden, the lighting is poor, or the observer has little experience identifying reptiles.
A frightened
