What kind of figurative language is the underlined phrase below Its hair which hung about its neck and down back was white as if with age yet face had not a wrinkle in it?

The underlined phrase "white as if with age" is a simile.

Here's why:

* Simile: A simile is a figure of speech that compares two things using the words "like" or "as". In this case, the hair is being compared to something that is "white as if with age".