Thank you for the reference @sbusse19 ! Could you share a quoted excerpt with the part saying that transposons cannot exist outside of the chromosome? I found the following which has to do with transposons relocating and it seems to imply that they can, at least temporarily, exist outside of the chromosome: “such transposons are able to cut themselves out of a bacterial nucleoid or a plasmid and insert themselves into another nucleoid or plasmid”