Mud monsters are brownish-red goop, resembling melted chocolate, with yellow eyes. The goop is constantly oozing from them, but never being seen left on the floor. When stunned, their two yellow eyes will be replaced with an "x", one bigger than the other.
Mud monsters first appear in level one. They do not attack at all but will kill the player on contact. Mud monsters will slide aimlessly around the level, and will not follow nor attack the player. To be eaten, they first need to be hit by a block. Then, while they are stunned, the troll can walk up to them and swallow them, gaining one hundred points.
A common glitch with most enemies, including the mud monster, in Square Meal is that they are seen walking through walls and blocks.
Going along with the food theme of Square Meal, the mud monsters might be made of gravy or melted chocolate.