A childhood belief about general

I spent a year teaching foreign 14-year-old children from developing countries in Spain, and I had many stories about that.
The one I prefer deals with fabulous creatures. I was asking children to make a list of fantastic animals. Then, a couple of girls from Dominican Republic asked me to add dinosaurs to that list. "But there were dinosaurs, once upon a time", I argued. "No, they weren't, they are in pictures only". "So, you think they are fabulous, as mermaids are?" Then, a girl from Equatorial Guinea cut in: "excuse me, teacher, but mermaids are not fabulous. I've seen them many times swimming in the rivers."