In Ex Nihilo, there are different ways of obtaining crops for food, such as potatoes, or plants such as trees. Naturally, it would be difficult to obtain a potato or carrot for example while using a Skyblock map. Ex Nihilo solves this problem by making certain crops obtainable by sifting dirt and getting seeds instead of whole crops.

For example, you may get a potato seed after a sifting attempt, which you can use to grow a potato like normal.