Is this a simile, metaphor, personification, alliteration, onomatopoeia, or hyperbole?
my dad is a rock; he never changes his mind once it's been made up.

karen blumenthal is the author of steve jobs: the man who thought different, and because of her work, she was a finalist in the 2013 yalsa award for excellence in nonfiction award.

it is significant that blumenthal interviewed several people who knew steve jobs personally because this allowed her to gain access to the industry. she has also stated that due to her work in the 1980s, she was able to get acquainted with the process of making computers and other technology, and was able to witness the progress different companies made and to appreciate apple's contribution to it. finally, this close connection with the industry means that her information is more credible than that of a complete outsider.