Uchuulon

An uchuulon, sometimes known as a slime chuul, was the result of a chuul partially undergoing ceremorphosis.

Description
Uchuulons resembled ordinary chuuls in size and shape: a hideous combination of crustacean, insect, and serpent some long and weighing approximately, with a mass of tentacles in front of the mouth, two large claws, and a fanned tail. They differed in that their carapace was softer, translucent, and coated in a thick mucous.

Behavior
Uchuulons were more intelligent than their monstrous appearance suggested, but they were also malevolent and wild.

Abilities
Slime chuuls were naturally amphibious like their regular kin, but they were weaker and clumsier, and slower on land. Additionally, their carapaces were softer and easier to pierce with weapons, though they made up for that lack with their protective coating of mucous. The mucous completely dissolved within one hour of separation from the uchuulon's body. They also had the same paralyzing tentacles as the more common form.

Combat
Uchuulons were ambush predators: they hid within a slimy pool of water until a creature came within reach, then surged up to seize it.

Ecology
Uchuulons were made, not born: each started life as a regular chuul, but at some point they were implanted with an illithid tadpole and began to undergo ceremorphosis. However, as chuuls were not suitable hosts for illithids, the tadpole invariably died partway through the process, leaving the chuul reduced to an uchuulon. Illithids created and used slime chuuls as lair guardians and hunters, finding them easier to manage than regular chuuls.