Asci of Ascobolus
Ascobolus is a Sac fungus that grow prolifically on herbivore dung (i.e. coprophilous). It can be found in almost any pasture during wet weather. There are eight ascospores in each sac (ascus) and as they mature they become thick-walled with a dark purple pigment that protects the spores from ultraviolet radiation during airborne dispersal. In the young asci the spores are still developing and have not yet become pigmented.