I thought of this not that long ago, a new configuration option for the "eating" kind of creatures. In the configuations tab for the elements Yam Yam, Dark Yam Yam, Pac-man, Mole, Pig, and any other element that can "eat" other elements, there could be a place to put an element, or maybe a list of elements that it can eat when running into. So, you could make a Pac-man eat Biomaze or a Yam Yam collect dynamite.
Here is how I imagine the interface:
If the player doesn't change the content, it is at default. Yam-Yams eat diamonds, Pac-Men eat amoeba, Dark Yam Yams eat pretty much everything...