【 Lore 】

Origin

Worms all originate from a massive juggernaut worm sphere, an amalgam of furry worm like creatures forming a powerful hivemind destroyer.
Worms rarely separate from their main body, the Motherworm.
When one individual cell discovers a conscious thought, the worm suddenly detaches from the Motherworm, and begins to develop it's own sense of self.
When this occurs it is often called "Going off the string".

Growth

Worms do not grow out of their larval stage until they go off the string.
But once detached, the worm will begin to grow limbs, reaching a juvenile stage, and finally, a fully grown form.

Diagram by Archeopsmaster

When a worm reaches it's adult stage, it gains the ability to spaceshift, able to stretch, retract, shrink, and grow, it's body in any manner, or any shape, and even texture, it desires. As they lack bones, this opens possibilities to many different preferred forms.
Worms are extremely mobile in their adult forms, being able to walk on two legs, four, or slither like snakes on the ground.

When worms reach maturity, they may also gain psychic abilities, due to their god like origins.
With their original form being the Motherworm, a creature capable of various psycho abilities, such as telekinesis, levitation, telepathy, the 'offspring' worms, will also often evolve into these abilities, over vast amounts of years.

Unfortunately, separation from the Motherworm is not tolerated, by the original lifeform.
The Motherworm will often send out small armies of larval stage worms to deal with and absorb any 'rebellious' offspring.