Acarosporina

Acarosporina is a genus of plant-parasitic fungi in the family Stictidaceae. The genus was created in 1977 and contains five species. These fungi form small, cup-shaped fruiting bodies that break through the bark surface of infected trees. They are typically found on damaged or diseased bark, particularly on cankers of oak, beech, and maple trees. The genus is distinguished by its unusual ascospores, which break apart into numerous tiny fragments inside the fruiting body....read more on Wikipedia.