Caecilia Worm

Bite. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) piercing damage, and the target is grappled (escape DC 14). Until this grapple ends, the target is restrained, and the worm can't bite another target.

Swallow. The worm makes one bite attack against a Medium or smaller target it is grappling. If the attack hits, the target is swallowed, and the grapple ends. The swallowed target is blinded and restrained, it has total cover against attacks and other effects outside the worm, and it takes 7 (2d6) acid damage at the start of each of the worm's turns. If the worm takes 15 damage on a single turn from a creature inside it, the worm must succeed on DC 15 Constitution saving throw at the end of that turn or regurgitate all swallowed creatures, which fall prone in a space 5 feet of the worm. If the worm dies, a swallowed creature is no longer restrained by it and can escape from the corpse using 10 feet of movement, exiting prone.