Sepedonium

All you see with the naked eye is a bright yellow powder.

Species of Sepedonium are generally parasites of boletes (or bolete relatives) and commonly you see evidence of the genus as a bright yellow powdery mass on a smelly, decaying bolete. That powdery mass is composed of thick-walled asexual spores and it is common to see them on the ground or underlying, leaves, litter, etc.

You are also likely to see areas of finer, white powder. There, the same fungus has produced colourless, thin-walled asexual spores.

Occasionally you may also see what look like very small, dark, glassy balls (and for this a hand lens that magnifies 10 times is very useful). Each ball is under a millimetre in diameter but sometimes a large number appear together, and a group is easier to spot. In each ball the same fungus is producing sexual spores.

Because the three states are macroscopically and microscopically different, the three states were originally given separate genus names.