In biology, particularly cell biology, the term organelle is used to describe any one of a number of types of subcellular structures, historically identified through the use of some form of microscopy.
A few large organelles probably originated from endosymbiont bacteria:
... units at an average density of 136.8/km² (354.8/mi²). The racial makeup of the town is 95.24% White, 0.93% African American, 0.13% Native American, 0.93% ...