n large amphibious mindless ooze swarm 

Perception +3; motion sense 60 feet, no vision

Skills Stealth +1 (+3 in water)

Str +0 Dex -2 Con +3 Int -5 Wis +0 Cha -5

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

AC  9; Fort +8, Ref +1, Will +3

HP 35; Immunities acid, mental, precision, critical hits, unconscious, visual

Speed 5 feet, climb 5 feet, swim 10 feet

Swarming Slither [>] The amoeba swarm slithers over each creature in its space, dealing 1d6 acid damage (DC 14 basic Reflex save). A creature that critically fails is sickened 1.

Weak Acid An amoeba's acid damages only organic material—not metal, stone, or other inorganic substances.

Bestiary 2, page 192. Expanded in LOIL.