Microfungi as a group are ubiquitous but not often noticed.  The photograph below of Golovinomyces fischeri shows conidiophores, on the underside of the leaf of a plant of Senecio vulgaris,  which are less than one tenth of a millimetre tall.

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith