Slime

Slime (スライム, Suraimu) are a type of Monster that is indigenous to labyrinths. They are shape less organisms. They don't seem very strong, but they can manipulate their shape to mimic others and boost their own fighting strength. The slime can come together and form a King Slime. In the anime as being labyrinth creatures of the Dungeon, Amon, they are capable of spewing fire from their mouths.