Cerebellar purkinje cells
The cerebellum, its name meaning “little brain” in Latin, really does look like a smaller brain located just below the back of the occipital lobe. The cerebellum is often ignored in research (MRI researchers are especially guilty of ignoring activations back there). It seems to be involved in coordination and balance, but likely has other purposes as well.
In cross-section, the cerebellum itself looks like a tree, and the neurons inside of it (purkinje cells, named after the anatomist who first studied them) are definitely very tree-like. You can see the yellow neurons here have some big extensions like a tree trunk and then many, many branches off of them, just like trees do. It’s less obvious how very tree like they are in this image as they cover and overlap each other, but I thought this picture was beautiful nonetheless!