FYI: appendix contains immune tissue and may not be completely vestigial. Recurrent laryngeal nerve is something that goes from high up in the brainstem all the way down the neck, then ascends all the way back up and finally innervates its target in the upper neck. The cause: evolution from amphibians (or fish specifically? I’ve forgotten) to mammals. Also, retinal development is an example of ~ridiculously complex and non-intelligent design given the cell layer order.