Mycelarium gives you food from four places: food pockets underground, pale salt rocks scattered through the soil, leaves that fall on the forest floor and decay into food, and specialised mushrooms that produce it on their own. The important part is that food, not water, is the resource that actually runs out — salt rocks are finite, and once they are gone you need a renewable source or the run stalls.
Mycelarium how to get more food: the four sources
- Food pockets. Buried underground, and one of the things the first expedition is looking for.
- Salt rocks. Pale rocks scattered through the ground. They give food, but early on they do not give a lot, and they run dry.
- Fallen leaves. Leaves drop on the forest floor and decay into food. This is the renewable source, and it is behind an unlock.
- Food mushrooms. Predator and carnivorous mushrooms produce food on their own once you have them unlocked.
The part of the run that actually starves you
Early game you are kind of starved: the salt rocks do not give much, and once they are exhausted you are left with nothing until the renewable source is running. Players put it plainly — water is never a problem, all is about food. One playthrough ran out of food with no salt left nearby and had nothing to do about it.
The fix is the unlock that turns falling leaves into food. Until you have it there is no renewable source at all, and the run depends on the salt you have not used yet. How to get that unlock working is in leaf mulching.
Mushrooms that cost food and pay food back
A food mushroom is an investment, not a free lunch. A Predator Mushroom set down for 20 food was reported to produce 25, which players judged a poor return, and a carnivorous mushroom placed early was taken by a hedgehog about ten seconds later. Mushrooms are worth having even when they do not pay for themselves, because you also need them to get past rocks.
The full list of mutations and what each one produces is in the mushroom mutation list.