Thoughts about a small eco system

[Tika96]

The living inside the asteroid is a bit too peaceful for my taste ( my duplicants do not agree with me here ). We have already Pokeshells who defend their eggs. And we have Shove Voles who "dig" through the asteroid and munch on your iron ore.

A nice step ahead would be a similar creature ( for example an transparent acid covered, acid spitting worm ). It has some kind of nest ( defending the surroundings ). It can actually digs tunnels ( but doesn't go far from its nest if not interfered or forced in other ways). It harvests plants like some ants do. The nest houses a couple of these worms. Depending on the diet, the excretion makes the surrounding suitable for the eaten plants ( atmosphere, extra fertilizer, even temperature ).

Another creature shares the habitat of the worms. But this creature ( for example a cute ball of whool ... no eyes, but a round mouth full of many rows of sharp, pointy teeth ) is a predator. It feeds on any other critter to distinction, the dropped meat and attacks duplicants. The only exception is the worm: Worms are herded like pigs by the whool ball. They will only feed on them if the number of worms are more than twice than the whoolies. Their excretes work like a booster to plants: They grow like being domesticated and start to spread ( not like pips, but to neighboring empty spaces ).

A third creature is living in this eco system. But you will need a magnifying glass. It's a small parasite living on any plant and within the worm and whool ball. The worm is unharmed by the parasite. But for plants and the whool critter it can be dangerous if the number of parasites gets too high: The number is normally slowly dwindling down to a small minimum. But every contact with an infected creature increase the number of parasites. Too many worms: Plants are dying - worms starve to a smaller group. Too many whoolies: Whoolies are dying until the number is lower again. Additionally the plants are thinned. And their growth cycle is slowed down. 

How about duplicants ? Duplicants infected by the parasite is at first quite harmless. The bad thing is, duplicants have many contacts per day. So the number of parasites is quickly exploding. Some other critters could die off the parasite while others are immune. Plants in greenhouses will need to be uprooted disinfected and replanted. The good news are, the duplicants can not die off the parasite, they feel a bit exhausted ( the skills are slightly reduced after some time) and the parasite is not spreading by inorganic materials ( any gases, any fluids, almost all solids). The bad news are, the duplicants can't get rid of it without medical treatment and they need to be isolated for some time before the parasite is completely removed from their bodies.