Parasite

Parasites are hardy creatures native to Tallon IV, selected for Phazon mutation by the Pirates, for their resistance.

Parasites do almost no damage. At the beginning of Metroid Prime, they are encountered in swarms, where the splatter they create can impede vision, but little else.

Oddly, though they are repeatedly stated to be indigenous to Tallon IV, they are never found once Samus makes planetfall.

Parasites also appear in Metroid Prime Pinball, albeit heavily redesigned for an unknown reason.

The Scarab enemy behaves similarly to the Parasite, attacking in great numbers.

Parasite
The Parasite is an interstellar vermin that travels in swarms and is indigenous to Tallon IV. A single Parasite is harmless to larger life forms. However, they tend to travel in large groups, swarming over potential prey.

Plated Parasite
Hardy member of the Parasite family. Invulnerable to most weaponry. A cousin to the Parasite, these stupid creatures are known for their amazing resilience. Field studies suggest a weakness to Morph Ball-delivered weapon systems.

Ice Parasite
A simple scavenger life-form that possesses a crystalline outer shell. Parasites are hardy creatures, able to adapt to any environment within three generations. The Ice Parasite is a prime example. Having adjusted to a frigid climate, this vermin now thrives in it. Omnivorous, it can exist in areas hostile to most life-forms.