5e SRD:Gray Ooze
From D&D Wiki
|This material is published under the OGL|
Medium ooze, unaligned
Skills Stealth +2
Amorphous. The ooze can move through a space as narrow as 1 inch wide without squeezing.
Corrode Metal. Any nonmagical weapon made of metal that hits the ooze corrodes. After dealing damage, the weapon takes a permanent and cumulative -1 penalty to damage rolls. If its penalty drops to -5, the weapon is destroyed. Nonmagical ammunition made of metal that hits the ooze is destroyed after dealing damage.
False Appearance. While the ooze remains motionless, it is indistinguishable from an oily pool or wet rock.
Pseudopod. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 4 (1d6 + 1) bludgeoning damage plus 7 (2d6) acid damage, and if the target is wearing nonmagical metal armor, its armor is partly corroded and takes a permanent and cumulative -1 penalty to the AC it offers. The armor is destroyed if the penalty reduces its AC to 10.
A gray ooze is stone turned to liquid by chaos. When it moves, it slithers like a liquid snake, rising to strike.
Variant: Psychic Gray Ooze
A gray ooze that lives a long time can evolve to become more intelligent and develop limited psionic ability. Such occurrences are more common in gray oozes that live near psionic creatures such as mind flayers, suggesting that the ooze can sense and mimic psionic ability.