Dirt Earthworm

For all the menace in its voice, Dirt Earthworm is nothing grander than a reddish earthworm, small enough to sit in a person's hand.

The creature brimmed with self-assurance and resented humankind for paving over the planet's soil with concrete. Its voice rose from beneath the ground in a deep, intimidating rumble that belied its tiny frame, and it fully meant to seize dominance on behalf of the natural world.

Dirt Earthworm surfaces in OVA 7, appearing after Saitama meets the Mediocre Ability Users and the group comes to terms with its own weakness. Its underground thrashing rattles the earth hard enough to trigger an evacuation, and it declares to Saitama and the others its disgust at humanity's concrete and its wish to rule. Though its body is minuscule, it can shift enormous volumes of soil, and it raises a towering wall of dirt to flatten them, only for Saitama to stop it cold. Saitama gives chase and drives a punch into the ground, but the worm's small size lets it wriggle aside and escape.

It later reappears to watch Saitama drill the Mediocre Ability Users, crowing that nature is on its side. While it is busy gloating, a passing sparrow snatches it up and gulps it down, ending its life moments after it named nature its ally. Its mastery of soil was genuine, yet its body proved as fragile as any common worm's.