Like Like (5e Creature)
From D&D Wiki
Large plant, unaligned
Skills Stealth +1
Amorphous. The like like can move through a space as narrow as 1 inch wide without squeezing.
Amphibious. The like like can breathe air and water.
Digestion. Any nonmagical weapon, shield, or armor that is swallowed by the like like has a chance of dissolving beyond repair. At the start of each of the like like's turns, roll a d6 for each object that is swallowed by the like like, and worn or wielded by a creature that is swallowed by the like like. On a 6, the object is destroyed. The like like's digestion ceases while it is incapacitated or otherwise unable to take actions on its turn.
Slam. Melee Weapon Attack. +5 to hit, reach 5 ft., one target. Hit: 9 (2d6 + 2) bludgeoning damage.
Swallow. Melee Weapon Attack. +5 to hit, reach 5 ft., one creature of smaller size than the like like. Hit: 9 (2d8) acid damage, and the target is grappled (escape DC 15). Until this grapple ends, the target is blinded and restrained, it has total cover against targets outside the like like, and the like like can't swallow another target. While grappled, the target takes 9 (2d8) acid damage at the start of each of the like like's turns. While the target is swallowed, the like like can't use its swallow action. If the target escapes this grapple, it must succeed on a DC 15 Dexterity saving throw, or drop everything it was holding into the like like, further subjecting the objects to the creature's digestion trait.
Resembling giant sponges, like likes can be found in almost any environment, but are most abundant underwater, near coastlines, or in dank caves. They mindlessly devour anything that moves into their huge, tubular mouthes, with the intent of dissolving whatever it might be while it's still alive. The acids in its stomach can break down seemingly any material very rapidly. Even if an adventurer escapes this monster's gut alive and slays the beast, he might lose his shield, his rupees, or even his armor to its digestive acids.
Ambush Predators. Most like-likes idly wander in search of anything that moves, but a rare few use something resembling strategy. These few use their amorphous form to squeeze into narrow holes in the ground, or other such crannies. When potential prey wanders by, the like like waits until the last possible moment before abruptly popping out and devouring its victim whole.