[[why does Mayuri always have things on his ears?]]
YES here we go! Some headcanons about Mayuri’s ears.
The very first body-modification Mayuri did to himself was the removal of both external ears. It was done because of several experiments. He had long been interested in being able to regulate his hearing, making it selective. ( He didn’t want to hear all the noise the other children at the orphanage was making ). The first ear pieces that he designed were simply meant to selectively make him hear only the things he wanted to hear. When people of a certain age and reiatsu pattern made a sound, he couldn’t hear it. He also used his ears in several experiments.
Another good thing about the removal of his external ears was that it made painting himself a lot easier.
Throughout his life, he has changed up his ear pieces, giving them different functions. He has also modified his ear canal.
Mayuri can remove his ear pieces completely, including the ‘ inner ‘ one, but removing the latter disturbs his hearing.
All his ear pieces have the function of giving him selective hearing, when he wants things to be quiet.
As for the aesthetics of them - Mayuri always goes with a gold design for them, as Mayuri simply likes the color. He likes a certain consistency to his color theme ( the gold matches his eyes ), because otherwise it would look messy ( hence why he only paints himself black/white ).