Stemonitis sp.

Scientific name:  Stemonits Gled.
Derivation of name:  
Synonyms:  
Common name(s):  Chocolate tube slime; Tree hair; Pipe
cleaner slime.
Phylum:   Myxomycota
Order:   Stemonitales
Family:   Stemonitidaceae
Occurrence on wood substrate:  Clustered on dead
wood and leaves; May through October. 
Dimensions: These slime molds are 1-1.5 mm wide and
up to 2 cm tall.  
Description: The brownish, cylindrical top portions
(sporangia) are supported by narrow, black stalks.        
Edibility:  Inedible.
Comments:  Chocolate tube slime look like brown hairs
growing on wood. While not fungi, slime molds often
form spore-bearing structures that resemble those of the
true fungi. Although many slime mold species fruit on wood
they do not form a penetrating and absorptive mass of
hyphae in the wood substrate. Rather, slime molds form
structures called plasmodia which are naked (i.e., without cell
walls) masses of protoplasm which can move and engulf
particles of food in an amoeboid manner. Slime mold
plasmodia creep about over the surfaces of materials,
engulfing bacteria, spores of fungi and plants, protozoa, and
particles of nonliving organic matter. At some point,
plasmodia convert into spore-bearing structures. In
Stemonitis, the plasmodium converts into a clustered mass
of stalked sporangia.

More information at MushroomExpert.com:   

    
Figure 1. Occurrence of Chocolate tube slime on a dead
log. The wood serves as a platform on which the
plasmodium forms numerous stalked sporangia.

Figure 2. There are several Stemonitis species. They vary in
relative length of the stalk and in microscopic details such as
spore morphology. Stemonitis species form stalked
sporangia filled with spores.

Figure 3. Appearance of the sporangia following release of
the spores. Attached to a central columella is a network of
capillitial threads.