The correct answer to this question is mold. A mold is a fungus that has the structure of multicellular filaments. Molds are a group of fungal species that cause a fussy appearance or discoloration when they start growing on certain materials. One of the characteristics of molds is that they absorb food from other sources.
Molds are formed from spores, and they begin to float in the air until they fall on some particles where they start growing. For instance, as they float in the air, they can easily land on any materials such as a piece of damp food. The moment they fall on any materials, they begin to grow into molds.
As they are growing on the materials, they are also releasing chemicals. For instance, in the case of food particles, they cause the food particles to break down, and in the process, the food particles begin to rot. Invariably, molds grow by absorbing food from different materials.