If you look at how cells work they're little factories with the complexity of a city. The small structures in a cell are the size of a person or a car while the cell itself is the size of a city. There are different organs inside that are specialized. It's full of little robots that perform various functions like the ribosome which takes mrna and poops out proteins. If materials are needed in one part of the cell it builds rods and then transports materials on them and destroys the rods afterwards. Mitochondria are like little life forms inside cells with their own genetic code separate from that of the cell. The nucleus governs much of the cell's functionality and the cell has a set of tools to work with DNA, repair it and copy it. Finally, the cell has the capability to self-replicate--an amazing feat. Trillions of such cells work together by communicating using both chemical (hormones) and electrical means (nerves) to create larger life forms such as humans. Not only can the mitochondria and cells replicate but the multi cellular structures as well. This is the result of billions of years of evolution. To me this is all absolutely incredible. It's nanotechnology all the way down. Life forms are machines for extracting energy from the environment and turning it into copies of themselves. Almost every place on the planet is teeming with life. You dream of grey goo that can adapt and replicate. We are it.