Molten

A Molten is a Hardmode slime-like enemy that starts to spawn as lava pools in the cavern layer become bigger and then into the Underworld. In other words, it spawns in lava in the Cavern layer and also in the Underworld.

The Molten has the ability to "flow" through walls. When stationary, it cannot go through walls, like a regular slime, but when it jumps, it can noclip for a very short amount of time towards anywhere or the player in a slithery motion before being either in an opening or stuck in blocks. When it does get stuck in blocks however, it will not suffocate, and will stay there until it will be able to noclip again. They are immune to the aforementioned suffocation, On Fire!, Burning, and Cursed Inferno.