Mineral Ooze

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

False Appearance. While the ooze remains motionless, it is indistinguishable from an oily pool or wet rock.

Mineralize. As a bonus action when it has encased a creature, the ooze hardens the minerals in its body, turning the surface of its body into a stone-like material. While mineralized, the ooze has a walking speed of 5 feet, and it has resistance to bludgeoning, piercing, and slashing damage. The ooze remains mineralized until the creature it has encased dies, or until the ooze takes a bonus action to end it.

Multiattack. The mineral ooze makes two slam attacks. If both attacks hit a Medium or smaller target, the target is grappled (escape DC 12), and the ooze uses its Encase on the target.

Pseudopod. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 6 (1d8 + 2) bludgeoning damage plus 3 (1d6) acid damage.

Encase. The mineral ooze encases a Medium or smaller creature grappled by it. The encased target is blinded, restrained, and unable to breathe, and it must succeed on a DC 14 Constitution saving throw at the start of each of the ooze's turns or take 7 (2d6) acid damage. If the ooze moves, the encased target moves with it. The ooze can have only one creature encased at a time. An encased creature can try to escape by taking an action to make a DC 12 Strength check. The creature has disadvantage on this check if the ooze is mineralized. On a success, the creature escapes and enters a space of its choice within 5 feet of the ooze. Alternatively, a creature within 5 feet of the ooze can take an action to pull a creature out of the ooze. Doing so requires a successful DC 12 Strength check, and the creature making the attempt takes 7 (2d6) acid damage. The creature making the attempt has disadvantage on the check if the ooze is mineralized.