What do different measurements/units of marijuana look like?

I don’t really smoke and have never bought weed so I don’t know about this sort of thing. When I overhear people say a “gram” or an “eighth” or an “ounce” (usually in films), what does this look like?

Google images is not helpful as it just shows pictures of all sorts of weed (when I google “eighth of weed” I get pictures of extreme close-ups or ridiculously large quantities). Other websites try to explain things by saying, “well, an eighth is X many grams” but this goes over my head without a visual.

I’d love to know where I can see pictures or get VISUAL (not numeric) descriptions of what these measurements look like so when friends, movies, rappers etc talk about this sort of thing I can imagine what they’re talking about. Also, so I don’t feel like a confused square anymore.

Thanks!