Soredia (sing. soredium) are powdery, roughly spherical growths composed of thread-like filaments of fungi (hyphae) that wrap around algae and/or cyanobacteria cells of a lichen. They are one of the ways lichen can reproduce themselves asexually. [Photo courtesy of Flickr user George Shepherd. Released under a Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Generic License.