If I see something, and I see it growing, I know it's alive. I see a baby grow from an infant to toddler to teenager and adult. I know it is alive. I see plants shoot up through the dirt, grow leaves and flowers, and I know it's alive. I see a rock, and all it does is stay the same or slowly erodes. It's not alive.
But some things are far more mysterious. What about viruses? Are they alive?
What is life?
Now take a look at this very interesting video about some things that sit on the boundary between living and non-living.
.
