Here is one of the slime monsters I've used in my DF Felltower game. My players have figured out all about it, and since I posted about Icky Goo yesterday I wanted to add some of my own goo to the mix. I didn't write this in "standard" monster form because it's a hazard more than a monster.
Why pink slime? It was all over the news when I wrote that section of the dungeon.
Why not green? A change is as a good as a holiday.
Pink Slime. This slime is red-pink in color and is finely textured. It smells slightly of meat (beef, perhaps) and is very greasy looking. It does 1d corrosion damage per second to anything that it falls on, touches, or is touched by. Does not affect stone or metal; DR with Tough Skin does not protect. Materials damaged or destroyed by pink slime immediately turn into pink slime - it doesn't just digest you, it transforms you!
HT 12, 3-8 HP (1d+2) depending on size, Move 1 yard per minute.
It's threatening but generally harmless to prepared delvers. Unprepared ones, well, sometimes you get the slime, sometimes the slime gets you. It's cancer-causing if you burn it to death and then try to eat it. Not that anyone ever tried that . . .