Formal i think i am not really sure
<span>"and his smile showed red lips and pointed teeth." is a good hint.
If you think about it, this line is the only one that would be used to describe an animal.
You can ask yourself, what do you think of when you read that line.
When I read it I could almost imagine a predator like a wolf snarling, showing it's vicious teeth. In effect, when he opened his mouth to smile it's like you're getting a glimpse into him and his nature.
</span>
By noticing how the character interacts with other characters and <span>by noticing details about what the character says, does, and thinks</span>
