Corpse Crawlers

Description:
Corpse Crawlers are a bizarre and disturbing organism. They aren't quite an animal, a plant, or a fungus - they exhibit properties of all three. Corpse crawlers are commonly found on planets with mild to cold climate and high amounts of death. 

Behaviors:
Once their victim dies, the crawler condenses their form to squeeze down their victim's throat. Once at the lungs, the crawler expands rapidly, puncturing the lungs and the surrounding organs. With room cleared, the crawler wraps its root-like tendrils around the skeleton, burrowing them firmly inside. Full control over the body allows the crawler to disguise itself as the creature the corpse is, giving the crawler an opportunity to deceive and kill - a new victim. Slowly, the corpse decomposes from the crawlers' unnatural feasting processes - absorbing every little bit of nutrients it can using its chemicals. (Side note: this chemical process creates a vapor that produces hallucinations in a vast number of creatures)

Properties:
Thankfully, the Corpse Crawler has one glaring weakness - humidity. Its fragile cell structure is unable to withstand humid environments. Whenever exposed to such an environment, the crawler's cells die off, reducing it to a pile of fleshy goop.