Bisporella sulfurina

Fresh fruit bodies are stalkless, bright yellow cups, with paler margins and exteriors. As they age, they become paler yellow or almost white.  they reach up to 1 mm in diameter.

They grow on old stromata of pyrenomycete fungi, especially those of the genera Diatrype, Diatrypella and Hypoxylon, which have, in turn, fruited on decaying wood from deciduous trees.  They grow gregariously on their host and often two or three will be seen tightly clustered together.

Usually found between summer and winter.