Hereās why:
1. They always have a structure that is FUNCTIONAL. It DOES something.
2. They move under their own power.
3. They grow.
4. They have repeating patterns and structures (such as leaves, vertabrae,
etc.). Quartz rocks have a certain general family resemblance, but pine
trees have not only a general resemblance to each other, but they also have
pine needles, thousands and thousands of them. Oh, and CELLS!! Lots and lots
of CELLS! Sometimes millions upon millions of cells, grouped in various
intricate ways.
5. Many of them replicate, more or less.
Can we refine this list?
Chris