Nearly all organisms live in symbiosis with a vast, diverse array of microbes. Arbuscular mycorrhizal (AM) symbiosis is the interaction between plants and a group of fungi called Glomeromycota. Most land plants, including several crop species, are able to interact with these fungi, which have been long known to positively affect plant growth and nutrition. The fungi live in plant roots where they elongate their tendrils (called hypha) into the surrounding soil, like an extension of the root system, to better access and transfer nutrients to the plant. In return the plant serves the fungus food made during photosynthesis.