Goolix

The Goolix is a mysterious, water-like lifeform that was discovered upon Captain Olimar's first visit onto PNF-404. The only other creatures described similarly to it it is the Waterwraith, the Plasm Wraith, and the Leech Hydroe - three other examples of gelatinous-based lifeforms found on the planet.

Biology
The Goolix, as a organism, doesn't follow the main rules of biology as other known organic lifeforms on PNF-404, as many rules that defy other creatures don't apply to the Goolix that much. It doesn't appear to possess any muscular, digestive or skeletal system.

Its body is made up of a transparent, gelatinous cell structure comparable to water. The only other "organs" it has is two orbs inside its body, which may serve as its nervous system.

From what information was provided by Captain Olimar, if the membranes are destroyed, then its body turned to normal water and loses all physical form. This provides theories that the actual creatures is the nuclei inside the Goolix, only controlling a water-like body to venture out onto land. If this theory is correct, then its a question on which nuclei is in control of the body.

Behavior
The Goolix itself has only been observed moving around on the surface. The smaller, solid form is seen being used as a defense mechanism for the Goolix. It uses its two nuclei to crush creatures in between, though it's theorized that this is actually self-harmful to the Goolix given the nature of the function of both nuclei.