Tamumus are feathered, flying creatures that are found in the Underworld and are commonly used as messengers, such as how pigeons and hawks are used to deliver messages over great distances. They were first introduced in chapter 43.
These creatures appear to be small and feathered with raptor like claws, and capable of flight. They have an ultramarine plumage on their main body and head, which gradually gradient off into purple towards the tips of their wings and tail feathers. They possess a mammalian shaped mouth with rows of white teeth, and also having hand-like structures at the mid-joint of each wing, suggesting that they may not be avian in nature.
These creatures are seen being used as couriers to send messages over long distances in the Underworld.