One of my players the other week died because they set foot in some yellow mold. The mold, being a weaker variety than normal, dealt less damage than it normally would have. After being burnt a little by its acid, they took note and decided to drop a torch on it.
Normally, it would have resulted in a normal bit of damage, but this mold happened to be underground in an extremely arid environment. The fire spread out, and burnt both the players for a tiny bit of damage, which unfortunately was more than the Minotaur ("reskinned" fighter) could bear. He died, leaving the cleric to flee back to the surface where the Minotaur's brother was waiting for the two of them to come out. When only the cleric returned, Minotaur II vowed to finish his brother's works.
Just a quick anecdote on one of my favorite player deaths. Set ablaze by a yellow mold's corpse! Classic.
