How to describe a growl-like sound in a frightening way?

People who search for cutesy ways to emphasize their stories often end up writing something that people laugh at for years.

He was as tall as a six foot three inch tree.
It skipped across the water exactly the way a bowling ball wouldn't.
Her face was elliptical, like a circle that had been gently squeezed by a Thigh-Master.

These are taken from high school essays and published on the internet and people have been laughing at them for decades. Try not to join them. Just write your story, and if you learn something new you can always change it later.