While out in the woods the other day I noticed these extraordinarily tiny mushrooms (class Agaricomycetes) growing on the bark of a tree. The caps were only about two to three millimeters in diameter. I suspect this fungus was taking advantage of some recent mild weather to disperse spores. I can’t imagine these fruiting bodies have since survived our return to sub-freezing temperatures.
The green lichens, which are themselves a type of fungus living in a symbiotic relationship with green algae, provide a sense of scale.