The Undelivered Messenger is a clone of Atoi, but with no face , and it's limbs and body aren't properly attached.
During the Desert Iota / Atoi come across another messenger , the messenger is found trapped in a ball singing to itself Iota/Atoi learn that it is a undelivered messenger that was trapped and left by it's own you. Iota/ Atoi progress through the level helping it and eventually freeing it.