Small monstrosity, chaotic neutral

Armor Class: 18

Hit Points: 180 24d6+96

Speed: 30 ft , burrow: 30 ft

STR

16 +3

DEX

11 +0

CON

18 +4

INT

3 -4

WIS

10 +0

CHA

11 +0

Damage Resistances: fire, poison; bludgeoning, piercing, and slashing from nonmagical attacks

Senses: Blindsight 60 ft, Passive Perception 10

Languages: Understands Common, and primordial but can't speak

Challenge Rating: 9 (5,000 XP)

Actions

Multiattack. The tiny tarrasque makes three attacks: one with its bite and two with its claws.
Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 10 2d6+3 piercing damage.
Claw. Melee Weapon Attack: +7 to hit, reach 5ft., one target. Hit: 6 1d6+3 slashing damage.   Chomp. The tiny tarrasque makes one bite attack against a creature of medium or smaller size.
On a hit the target must succeed on a dc 18 STR save or be grappled.