280 days of Urbpandemonium #83
By night Stemonitis* creeps along a damp rotten log, a mass of protoplasm engulfing and feeding upon bacteria and other organic cells. It can perceive the rising sun, and moves under the log to avoid drying out. At the end of it's life cycle, it crawls back to the top of the log, and its cells transform from undifferentiated amoebae into the structure you see above. The fruiting stage is called chocolate tube slime, and the slender tubes release spores into the air to begin the cycle again.
*"Little threads"