So I’m not sure the best way to explain this, will edit in one second
So basically some creatures have leftover bones or other features that have no benefit but they also aren’t detrimental, and they are the result of evolution. There is a great video on bad animal skeletons by Sam O Nella Academy, it has some strong languages so inappropriate jokes, probably, all of them do, and this is middle school biology so watch at your own risk, but I think a pint you could bring up that your teacher would be impressed by is really any animal with a weird skeleton, for example dolphins who just have a random bone image where their legs used to be, they obviously don’t have legs but their ancestors did and to this day they still have a random bit of bone where an ancestor of theirs used to have legs, so skeletons help connect what a common ancestor looked like to what the current species looks like through similar bone structure and/or left over bones, such as dolphins who have a plate where an ancestor used to have legs
Endorphins are brain chemicals
known as neurotransmitters which are released when the body feels a certain
amount of stress and pain. Endorphins alter the communication of pain in the
body by interacting with the opiate receptors and blocking the synapse so that signals
cannot be sent to the brain in order to reduce an individual perception of pain.