What are the structures called that anchor bread molds to their food substrate?

The structures that anchor bread molds to their food substrate are called rhizoids.

Rhizoids are root-like filaments that grow from the underside of the mold and penetrate the substrate. They are responsible for absorbing nutrients and water from the food source, providing the mold with the sustenance it needs to grow and reproduce.

It's important to note that while rhizoids look similar to roots, they are not true roots. True roots are found in plants and have specialized tissues for water and nutrient absorption. Rhizoids are simpler structures found in fungi and other organisms.