National Geographic recently put up a pictorial about all the different glow-in-the-dark critters (and their proteins, neurons, etc.) and how they have contributed to science.
Go Mother Nature!
I love this one of the mice neurons. It’s so pretty, and they’re color coordinated to show where and what the brain is up to. (Read more about the “brainbow“). The scientists started off with just three colors – red, blue and green – and the developing brain did the rest.