Shortly after the Cambrian Explosion discussed in chapter two (ok, actually about 181 million years later), a small fish of the Coccocephalus wildi species perished and became fossilized. The fossil, discovered about one hundred years ago was recently scanned using computed tomography (CT), and to their surprise, researchers discovered a somewhat perfectly preserved brain structure! Another small piece of the evolutionary puzzle! You can read about it here: https://www.cnn.com/2023/02/02/world/oldest-preserved-brain-fish-intl-scli-scn/index.html, and Nature published the study here: https://www.nature.com/articles/s41586-022-05666-1.