In the film, you don't see this performance of this gelatinous fiend in "Phantoms." In the novel by Dean Koontz, the creature is an amoeboid beast that imitates any lifeforms it has absorbed, much like the shapeshifter in John Carpenter’s The Thing. It can also sends drone or “phantoms” out of its gigantic bulk to hunt, attack, and can be recalled to the parent mass. This illustration of mine is based on one particular event in the Novel.

Come out of an air duct, it slowly comes pouring onto the floor and grows as more comes out, spreading across the room where the characters are. As it does so, it begins to form on its mass arms, legs, and small limbs. Then they melt back into the amorphous beast and form new things, never keeping still with its transformation. Now faces of humans, cats, dogs, other creatures, and even prehistoric beasts began to emerge from the shapeshifter, silently screaming. After a few moments, it stopped. Then came forth tentacles that were thin, fat, ropey, and some resembling like worms, or octopus. When that was done, after eating a cop, holes formed on the creature and issued sounds of every living thing it had ingested. After that, there is another event where eyes formed, then mouths.

Note: The writing is from my DeviantArt post, edited for clarity.