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:
... 33.8% from 25 to 44, 21.3% from 45 to 64, and 11.8% who are 65 years of age or older. The median age is 36 years. For every 100 females there are 96.3 males. For every ...