Colossal Moth Caterpillar

Spider walking - Has the ability to walk on any surface

Shell Protection - Can go inside shell for a +5 bonus to ac, adv on Str and Con saves but disadvantage on Dex saves

Massive Frame - The Caterpillar can carry 10,000 lbs of weight on its back, however at half speed when weight exceeding 5,000 lbs.

Multiattack. The caterpillar cand make a Bite attack and a Slam attack in a single action.

Bite. Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit: 16 (2d12 + 6) bludgeoning damage. If the creature is Large or smaller then they must succed a DC 18 Dex save or be Swallowed. A swallowed creature is blinded and restrained, it has total cover against attacks and other effects outside the caterpillar, and it takes 21 (6d6) acid damage at the start of each of the caterpillar's turns.

If the caterpillar takes 30 damage or more on a single turn from a creature inside it, the caterpillar must succeed on a DC 21 Constitution saving throw at the end of that turn or regurgitate all swallowed creatures, which fall prone in a space within 10 feet of the caterpillar. If the caterpillar dies, a swallowed creature is no longer restrained by it and can escape from the corpse by using 20 feet of movement, exiting prone.

Slam. Melee Weapon Attack: +10 to hit, reach 15 ft., any creature within 10 ft of one target. Hit: 34 (4d12 + 6) bludgeoning damage. All creature that are not the target must make a DC 18 Dex save or be knocke prone.