Martini with a Black Olive

Typically green pimento olives are served in a martini, but if you put a cocktail onion in it, it’s called a Gibson - what do you call it if it has a black olive in it? Does it matter? I thought there was a different name for it but cannot find anything after a half hour of searching. Fun fact: Vodka Martini is called a “Kangaroo” but no one knows it by that name?