Booger Monster

The Booger Monsters are a species of - likely non-sapient - slimy lifeforms that appear to be kept by certain individuals as perhaps large pets, mounts, or even gladiatorial creatures or guards.

Biology
As their name would certainly suggest, they are absolutely covered in a green phlegm-like sludge which serves an unknown evolutionary purpose for them, but it likely involves escaping predators or maneuvering through their natural habitats. They appear to be heavy, but not heavy enough to kill someone after falling from a significant height onto them.