The Astomi (or Astomoi) were a mythical tribe of mouthless people who lived near the mouth of the river Ganges and fed off the smells of flowers and fruits.
Okay, 'mythical' may be a bit of a stretch. A Greek dude named Megasthenes included the Astomi in his work Indica, where he wrote about India. While most of what he wrote was stuff he'd seen for himself when he went to visit, a lot of it is also just legends and stories he either heard or made up himself.
(For instance, according to the Indica, Dionysus and Hercules both visited India, and became known there as Krishna and either Shiva or Indra. Yeah. Sure.)
The Astomi are, as mentioned, mouthless. They're also covered in thick hair and, again, feed solely off the air they breathe and the smell of fruits, flowers, and roots. (When they need to make a long journey, they keep a bunch of the stuff with them for on the go snacking). They're also apparently pretty easy to kill, as all it would take is one really strong, really foul odor to make them keel over dead.
And that's pretty much all there is to these guys.