Beautiful. Dictyosteliida, a type of slime mold. They live as individuals until food runs out, then they form sporangia. They release a signal molecule into the environment that allows them to bunch together. They join into a tiny slug-like creature, which moves to an open place and develops into a fruiting body. Some of the amoebae become spores to begin the next generation, and some sacrifice themselves to become the dead stalk, thus lifting the spores up into the air for better dispersal.