Okay, that would be an awesome encounter to throw into a dungeon.
In Rappan Athuk there is a feces monster called Dungie that is almost impossible to kill. You can defeat it but it reconstitutes after a period of time. So you may have to keep running into it. Makes sense that this would attract a large group of otyughs to this infinite source of food. Next time my players pass by this way, they'll come accross a group of otyughs attacking and eating dungie.