In the 2015 clmooc map https://www.google.com/maps/d/edit?mid=zYeEwV7o_qjg.k1yQZAsgZuBo
is a list of names and pins. Some pins are colored or have different shapes. How could you do that?
Move your mouse in the list and you will see a tiny image after the name of the pin.
now you will get a pop-up
you could try to find a nice pin (delete pin and add new one is possible)
The option : more icons has a nice feature: add an URL of your own special picture as an icon .