I’m going to spoil one egg location for you. In world four, this is the only hidden egg that has a special rule attached. You have to press the fire button 16 times in a single second in honor of Takahashi Meijin. I had to use the autofire function on my controller, cranked up higher than I normally have it, and even then, it took me a while to figure out where to do it from. I gave up and looked it up in a guide, which said to not stand on top of it. It didn’t work. How did I finally get it? Standing on top of it.