The poles are part of Mario the atmosphere, there is no doubt about that. But there is one ghost in Super Mario 3D Earth that is unlike any other ghost. And because it's easy remember, most players don't even know they exist.
As explained in a recent video from YouTuber, SwankyBox, this volcanic spirit looks like a human being, appearing only at certain levels and seems to follow Mario on his journey throughout the game.
This strange ghost appears for the first time in World 4-4 of Super Mario 3D Earth for the 3DS. But the only way to see this ghost is to reach the end of the level and expect it to appear slightly behind the fence in the forest behind the level. Why is this ghost here? Neither knows. Another good question is why does this ghost exist? SwankyBox thought it might be a reference to the famous painting The Scream. Some have ideas that it has to do with the creepy figures seen inside Mario Galaxy. But nobody really knows what Nintendo didn't say.
While this ghost has turned into some well-known secret for Earth 4-4, not as many people know that this ghost actually follows Mario throughout the game, it has emerged on some spooky levels, usually in the end. Although it is initially found on another level, it is less visible outside the window.
Just add this clever bastard to the list of some of the most bizarre and awesome things that exist in Mario's games for some reason. It is almost like that many eels with that deadly piano.