I literally just finished Nausicaä of the Valley of the Wind yesterday, and honestly, the beautifully complex designs of the Ohmus as well as their mobilization and piercing eyes. I especially loved how their pupils turned red when they became aggressive and then blue when they eventually calmed down at the end of the movie. I believe this represents perspectives of nature and emotions (blue meaning calmness and red meaning anger) which is absolutely ingenious of Miyazaki Hayao to me.