Brown Jelly

Amorphous. The jelly can move through a space as narrow as 1 inch wide without squeezing.

Spider Climb. The jelly can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Noxious odor.  When a creature enters within 5 ft of the Jelly they must make a CON check DC 13. If failed the creature becomes ill and has disadvantage on all attacks.

Pseudopod. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 9 (2d6 + 2) bludgeoning damage plus 3 (1d6) acid damage.

Filth Spray. Ranged Attack: range 30 ft., one target. Dex save DC 13. Hit: 5 (1d6 + 2) poison damage

Split. When a jelly that is Medium or larger is subjected to lightning or slashing damage, it splits into two new jellies if it has at least 10 hit points. Each new jelly has hit points equal to half the original jelly's, rounded down. New jellies are one size smaller than the original jelly.