Worms (All Tomorrows)

 The Worms were one of the posthuman species created by the Qu from a colony of the Star People.

The Worms lived on the hot desert world that was once inhabited by their ancestors, but remade by the Qu into an even harsher world full of dead cities. But thanks to crystalline plants, there was still enough oxygen in the atmosphere for subterranean animals to survive.

Worms from All Tomorrows by C.M. Kosemen          

As their name implies, the genetic engineering of the Qu made these descendants of the Star People look like worms, barely longer than the arms of their ancestors. Their elongated bodies sported small arms and legs modified for digging. Their eyes were only small holes and they lacked teeth, external ears and most of the nervous system of their ancestors.

Lacking the sapience of earlier humans, they only dug through the ground, devouring everything they found, sometimes even other Worm People if they did not mate with them.

  After millions of years, the heat of their world         cooled down and animal life returned to the surface. The worms evolved into a species of tree-climbing 

snake-like creatures and eventually re-evolved human intelligence. They became the Snake People.

Source: aliens.fandom.com