Textbook says only the noble gasses exist in nature as single atoms. It also says that monatomic ions contain only one atom. That seems contradictory

Question

My textbook says the six noble gases are monatomic gases, and the only elements that exist in nature as a single atom. But on the next page it has a picture of the periodic table listing a bunch of monatomic ions that contain only one atom. Is the distinction that they don’t exist in nature? 

Answer 1

All atoms that exist in nature exist for at least a short period of time as single atoms. The periotic table doesnt show ions (monoatomic or otherwise).  It shows elements.