Jillyfish (5e Creature)
From D&D Wiki
Gargantuan beast, unaligned
Charge. If the jillyfish moves at least 20 feet straight toward a target and then hits it with a ram attack on the same turn, the target takes an extra 17 (3d8 + 4) bludgeoning damage. If the target is a creature, it must succeed on a DC 18 Constitution saving throw or become stunned until the end of its next turn.
Multiattack. The jillyfish makes two attacks, one with its ram and one with its tendril.
Ram. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 35 (6d8 + 8) bludgeoning damage.
A massive, jellyfish-like creature, found in underground bodies of water. On its bell is the faint impression of a woman’s face, which always seems to look upwards towards the surface.