This year's Nobel Prize in Chemistry was awarded to scientists who took a fluorescent protein from jellyfish and developed a technique to tag proteins with it, "shedding light," so to speak, on countless biological processes. One of those scientists, Osamu Shimomura, writes here about the early days of that research, cutting up jellyfish and extracting the protein.
And here is an example of an application of that technique, with some surprising findings about stem cells: