SEATTLE — It’s easy being green for a sea slug that has stolen enough genes to become the first animal shown to make chlorophyll like a plant. Shaped like a leaf itself, the slug Elysia …

If you’re thinking McLeod, you couldn’t be further from the truth. What you have to do is think small; not microscopic, just big enough to see with your naked eye. Turritopsis nutricula is a hydrozoan, …