Here's something I've thought about many times. Life started as single-celled organisms, right? Then, the cells learned to work together and thus multi-celled organisms were created. But, each cell is it's own life form. So, wouldn't that make us (and all multi-celled organisms) not an individual but a group of many (in our case billions of) individual, single-celled life forms? All working together like ants or bees.