n gargantuan mindless ooze 

Perception +23; motion sense 240 feet, no vision

Skills Athletics +27

Str +8 Dex -3 Con +6 Int -5 Wis +0 Cha -5

Motion Sense An amoeba swarm can sense nearby creatures through vibration and air or water movement.

AC  20; Fort +25, Ref +14, Will +19

HP 300; Immunities acid, mental, piercing, precision, slashing, sonic, critical hits, unconscious, visual

Split When a verdurous ooze that has 10 or more HP is hit by an attack that would deal piercing or slashing damage, it splits into two identical oozes, each with half the original's HP. One ooze is in the same space as the original, and the other is in an adjacent, unoccupied space. If no adjacent space is unoccupied, it automatically pushes creatures and objects out of the way to fill a space (the GM decides if an object or creature is too big or heavy to push).

Reactive Strikes [R] Trigger The carnivorous blob takes damage from any source; Effect The blob makes a pseudopod Strike against an adjacent target. If an adjacent creature dealt the triggering damage, that creature is the target of this Reactive Strike.

Speed 20 feet, climb 20 feet, swim 20 feet

Melee [>] pseudopod +26 (reach 30 feet), Damage 2d12+12 bludgeoning plus 2d6 acid and Grab

Carnivorous Blob Acid A carnivorous blob's acid damages only flesh—not bone, stone, wood, or other materials—but is nonetheless devastating. Whenever a creature takes damage from this acid, it must succeed at a DC 33 Fortitude save or become drained 1 (drained 2 on a critical failure). On each subsequent failure, the drained condition value increases by 1 (or by 2 on a critical failure), to a maximum of drained 4.

Constrict [>] 2d12 bludgeoning plus 2d6 acid, DC 33

Engulf [>>] DC 33, 4d10 acid, Escape DC 33, Rupture 20.

Bestiary 2, page 195. Expanded in LOIL.