Large colony of peritrichs (possibly Carchesium sp). 40x magnification. Darkfield microscopy.

Peritrichs are unicellular ciliated protists found in marine and freshwater environments. They can anchor themselves to a substrate individually or form colonies that attach to a surface with a stalk that may branch off to multiple degrees. Living in a colony and working together to survive, feed, and ultimately reproduce like these little protists can help give insights into the origin of multicellularity because early eukaryotic life (organisms with a nucleus and membrane-bound organelles in their cells) i.e. what we now know as animals, plants, and fungi depended on the development of multicellularity of many of their member organisms to survive. Humans wouldn't have been able to evolve without specialization of cell types and complex cellular networks that make up our tissues and organs, etc. The starting point for all of this was when individual cells of unicellular organisms began to work together and eventually through genetic changes, were able to divide together and carry on as single organisms made up of multiple cells that could carry out more complicated functions.